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DEPARTMENT    OF    THE   INTERIOR 


MONOGRAPHS 


OF    THE 


United  States  Geological  Survey 


VOLUME    LI 


Part  II.~PLA.TES 


MM  2     1962 


WASHINGTON 

GOVERNMENT    PRINTING    OFFICE 
1912 


UNITED  STATES  GEOLOGICAL   SURVEY 

(iEORGE   OTIS   SMITH,    Director 


/Ko^f 


-7    /- 


/At 


CAMBRIAN    BRACHIOPODA 


BT 


CHARLES  D.  WALCOTT 


Part   II.-I'L^TES 


WASHINGTON 

GOVERNMENT    PRINTING    OFFICE 
1912 


PLATE   I. 


PLATE  I. 

a.  Area.  s.  Median  septum  (see  flg.  47A,  p.  567). 
cl.  Cardinal  .scars.  t.  llidges  mcnUoncd  in  the  text  (see  flg. 

h.  Central  muscle  scar.  47A,  p.  5<i7). 

j.  Anterior  lateral  muscle  scars.  t'.  l)epres.sed  cardinal  area  (see  flg.  47A 
n.  Cast  of  short  ridge  in  aiivance  of  apex.  p.  5fi7). 

p.  Pedicle  furrow.  v.  Visceral  area. 

RUSTELLA    EDSONI  Walcott  (p.  327). 

Figures  1  and  la.  Casts  of  the  exterior  of  compres.sed  ventral  valves  from  Lotalily  25,  Lower  Cambrian,  Georgia, 
Vermont.  IT.  S.  Nat.  Mug.  Cat.  Nos.  51412a  and  51412b,  respectively.  Specimens  represented  by  figs. 
1  and  la  were  figured  by  Walcott  [lS8Gb,  PI.  IX,  figs.  Ih  and  Ig,  respectively;  and  1891a.  Tl.  LXIX, 
figs.  Ih  and  Ig,  respectively]  as  ventral  \-alves  of  Kutorrjina  rinf/iiUila.     Figure  1  is  the  type. 

lb.  Cast  of  the  interior  of  a  ventral  valve  from  Locahty  49a,  Lower  Cambrian,  York,  Pennsylvania.  U.  S. 
Nat.  Mus.  Cat.  No.  51463a. 

Ic.  Cast  of  the  interior  of  a  ventral  valve  from  Locality  25,  Lower  Cambrian,  Georgia,  Vermont.  U.  S.  Nat. 
Mus.  Cat.  No.  51412c. 

Id  and  le.  Casts  of  the  exterior  of  dorsal  valves  from  Locality  392o,  Vermont.  U.  S.  Nat.  Mus.  Cat.  No8. 
52035a  and  52035b,  respectively. 

CURTICIA    ELEGANTULA    Walcott  (]).  369). 

Figures  2,  2',  2".  Top  and  back  views  and  side  outline  of  the  exterior  of  a  ventral  valve,  the  type  specijien.     V.  S. 

Nat.  Mus.  Cat.  No.  51902a. 
2a,  2a',  2a".  Top,  side,  and  back  views  of  a  more  nearly  circular  \entral  valve  than  that  represented  by 

fig.  2.     U.  S.  Nat.  Mus.  Cat.  No.  51902b. 
2b.  Top  and  side  views  of  a  ventral  valve.     V.  S.  Nat.  Mus.  Cat.  No.  51902c. 

2c.  Partly  exfoliated  ventral  valve  showing  inner  layers  of  the  shell.     U.  S.  Nat.  Mus.  Cat.  No.  51902d. 
2d.  Posterior  view  of  an  elevated  ventral  valve  having  a  large  delthyrium.     U.  S.  Nat.  Mus.  Cat.  No.  51902e. 
2e.  Posterior  view  of  a  ventral  valve  wdth  very  low  delthyrium.     L".  S.  Nat.  Mus.  Cat.  No.  51902f. 
2f.  Back  vie%v  of  the  cast  of  a  ventral  valve.     U.  S.  Nat.  Mus.  Cat.  No.  51902g. 
2g.  Posterior  portion  of  the  cast  of  a  ventral  valve.     U.  S.  Nat.  Mus.  Cat.  No.  51902h. 
2h,  2i,  and  2].  Exterior  of  dorsal  valves  and  side  outlines.     V.  S.  Nat.  Mus.  Cat.  Nos.  51902i,  51902J,  and 

51902k,  respectively. 
2k.  Interior  of  a  dorsal  valve  with  a  trace  of  muscle  scars  near  the  apex.     U.  S.  Nat.  Mus.  Cat.  No.  51902  1. 
21.  Cast  of  the  interior  of  a  dorsal  valve,  retaining  a  portion  of  the  .shell.     L'.  S.  Nat.  Mus.  Cat.  No.  51902m. 

Another  specimen  (Cat.  No.  51902n)  was  used  also  in  drawing  fig.  21. 

The  specimens  represented  are  all  from  Locality  82b,  I'pper  Cambrian,  ''St.  Croix  sandstone,"  Taylors  Falls, 
Chisago  County,  Minnesota. 

Neobolus  warthi  Waagcn  (p.  566). 

[Te.xt  figs.  47A-B,  p.  567,  and  PI.  LXXXI,  figs.  2,  2a-h.] 

Figure  3.  This  specimen  is  figured  by  Waagen  [1885,  PL  LXXXIV,  fig.  7;  and  1891.  PI.  II,  fig.  8c]  as  the  interior 

of  a  dorsal  valve  of  Neobolus  warlhi.     It  may  possibly  be  an  old  shell,  worn  by  rolling  in  the  sand. 

Geol.  Survey  India  Cat.  No.  3/779. 

4  and  4'.  Exterior  and  back  views  of  a  specimen  of  the  ventral  valve.     Geol.  Survey  India  Cat.  No.  3/776. 

Specimen  figured   by  Waagen  [1885,  PI.  LXXXIV,  fig.  4;  and  1891,  PI.  II,  fig.  5]  as  Keobolus  unrlhi. 

4a.  Specimen  of  the  dorsal  valve.     Geol.  Survey  India  Cat.  No.  3/777.     Specimen  figured  liy  Waagen  [1885, 

PL  LXXXIV,  figs.  5a-b;  and  1891,  PI.  II,  figs.  8a-b]  as  Neobolus  warlhi.  ^ 
4b.  This  figure,  which  is  diagrammatic  and  incorrect,  is  replacedby  text  figure  47A,  p.  567.     Interior  of  a  dorsal 
valve  from  a  cast  made  in  a  natural  mold.     Original  in  the  collection  of  the  Geological  Survey  of 
India  (Cat.  No.  3/780);  cast  in  the  United  Slates  National  Museum  (Cat.  No.  56909a). 
5.  Ventral  valve  described  and  illustrated  by  Waagen  [1885,  p.  759,  PL  LXXXV.  figs,  la-c:   and   1891, 

PL  11,  figs,  lla-b]  as  Neobolus  vynnei.     Geol.  Survey  India  Cat.  No.  3/781. 
5a.  Dorsal  valve   described  and  illustrated    by  Waagen  [1885,  p.  759,  PL  LXXXV,  figs.  2a-<';  and  1891, 
PL  II,  figs.  lOa-b]  as  Neobolus  injtviei.     Geol.  Survey  India  Cat.  No.  3/782. 
All  the  specimens  from  which  the  above  figures  of  A'eoholus  V'arlht  are  drawn  are  from  Localitx'  357c.  the  A'eobolus 
beds  of  the  Khussak  group  of  the  Middle  Cambrian,  Kiura,  Salt  Range,  India. 
6 


U.  S.  GEOLOGICAL  SURVEY 


MONOGRAPH   LI     PL.  1 


.^^:^IF^^. 


^        A 


FRANCES  WIESER  DEL. 


LIOTVBE    CO    aCSICN 


PLATE  I.  7 

ScHizoPiiOLis  RUGOSA  Waagon  (p.  609) . 

[PI.  LXXXI,  fiRs.  l,la-c.) 
Figure  4c.  Interior  of  a  dorsal  valve  from  a  cast  made  in  a  natural  mold.  The  casts  were  obtained  first  by  dissolving 
the  shells  and  then  taking  wax  and  plaster  casts  of  the  uninjured  natural  molds.  From  Locality 
357c,  the  Neohohis  beds  of  the  Khussak  group  of  the  Middle  Cambrian,  Kiura,  Salt  Range,  India. 
Original  in  the  collection  of  the  Geological  Survey  of  India  (Cat.  No.  3/780);  cast  in  the  United  States 
National  Museum  (Cat.  No.  56910a). 

VOLBORTHIA   RECURVA    (Klltoi<;il)    (j).  366). 

[Textflss.  33A-B,  p.  366.] 

Figures  6,  Ga,  (jb,  6c,   and  Od.  Posterior,  side,   front,  ventral,  and    dorsal  views  of   the  type  specimen,  a  partly 
exfoliated  shell  which  has  the  two  valves  united,  from  Locality  336g,  Ordovician  glauconitic  lime- 
stone at  Zarskoe  Selo,  Government  of  St.  Petersburg,  Russia. 
6e.  View  of  the  false  area  of  the  ventral  yalve  represented  in  fig.^.  G,  Oa-d.     The  false  area  of  this  shell  haa 
been  illustrated  by  photography  in  text  figs.  33A  and  33B,  j).  3GG. 

Figures  6,  6a-e  are  copied  from  von  Moller  [1874,  PI.  VII,  figs.  1-6,  respectively].     Original  specimen  in  the  col- 
lection of  the  Museum  at  Reval,  Esthouia,  Russia;  cast  in  the  United  States  National  Museum  (Cat.  No.  58298). 


PLATE   II. 


PLATE   II. 

MiCROMiTRA  (Paterina)  BELLA  (Billings)   (p.  344). 

FiauRE  1.  Apical,  postorior,  and  fide  views  of  a  ventral  valve.  U.  S.  Nat.  Mus.  Cat.  \o.  51417a.  Until  the  speci- 
men represented  by  fig.  Ic  is  found  this  valve  may  be  regarded  as  typical  of  the  species.  (See  pp.  335 
and  350  and  fig.  6  of  this  plate.) 

la.  Summit,  po.sterior,  and  side  views  of  a  dorsal  valve.     U.  S.  Nat.  Mus.  Cat.  No.  51417b. 

lb.  Dorsal  valve,  showing  a  somewhat  more  elevated  beak  than  in  figure  la.     U.  S.  Nat.  Mus.  Cat.  No.  51417c. 

The  specimens  represented  by  figures  1,  la-b  are  all  from  Locality  49w.  Lower  Cambrian  limestone  one-fourth 
mile  south  of  Emigsville,  York  County,  Pennsylvania. 

FiuuRE  Ic.  Type  specimen,  from  Locality  2n,  Lower  Cambrian  limestone  bowlders  in  conglomerate  at  Trois  Pistoles, 
Quebec.  Copied  from  Billings  [lS72b,  fig.  13,  p.  477].  The  figure  has  been  widely  copied  (see  p. 
344),  but  the  specimen  from  which  it  was  drawn  can  not  be  located.  (See  pp.  335  and  350  and  fig.  6 
of  this  plate.) 

MiCROMiTRA  (Paterina)  labradorica  (Billings)   (p.  347). 

Figure  2.  Enlarged  drawing  of  the  type  specimen,  from  Locality  392a,  Lower  Cambrian  at  L'Anse  au  Loup,  Straits 

of  Belleisle,  Labrador.     Geol.  Survey  Canada.     Specimenoriginally  figured  by  Billings  [1861b,  fig.  6, 

p.  6]. 
2a.  Dorsal  valve.     U.  S.  Nat.  Mus.  Cat.  No.  18309a.     Specimen  figured  by  Walcott  [lS91a,  PI.  I.XIX,  fig. 

3b]  as  Kutorgina  labradorica. 
2b.  Posterior  view  of  a  small  ventral  valve.     V.  S.  Nat.  Mus.  Cat.  No.  18309b. 
2c.  Partly  exfoliated   shell  of  a  ventral   valve.       U.  S.  Nat.  Mus.  Cat.  No.  18309c.      Specimen  figured   by 

Walcott  [1891a,  PI.  LXIX,  fig.  3a]  as  Kutorgina  labradorica. 
2d.  A  more  elevated  ventral  valve,  which  has  been  partlj'  broken  away  along  the  cardinal  margin.     U.  S. 

Nat.  Mus.  Cat.  No.  18309d.     Specimen  figured  by  Walcott  [1891a,  PI.  LXIX,  fig.  3]  as  Kutorgina 

labradorica. 

The  specimens  represented  by  figures  2a-d  are  from  Locality  41a,  Lower  Cambrian  limestone  at  Topsail  Head, 
Conception  Bay,  Newfoundland. 

Figure  2e.  Dorsal  valve  from  Locality  3a,  Lower  Cambrian  shale,  on  Hanford  Brook,  St.  John  County,  New  Bruns- 
wick, Canada.     TT.  S.  Nat.  Mus.  Cat.  No.  5142Sa. 
2f.  Ventral  valve  associated  with  specimen  represented  by  figure  2e.     V.  S.  Nat.  Mus.  Cat.  No.  51428b. 

MiCROMiTRA  (Paterina)  labradorica  swantonensis  (W'alcott)  (p.  348). 

Figure  3.  Apical  view  and  side  outline  of  a  ventral  valve,  the  type  specimen.     U.  S.  Nat.  Mus.  Cat.  No.  1.5329a. 
3a.  Apical  view  and  side  outline  of  a  more  elevated  ventral  valve.     U.  S.  Nat.  Mus.  Cat.  No.  15329b. 
3b.  Dorsal  valve  associated  in  the  same  block  of  limestone  with  the  specimen  represented  by  figure  3a. 
U.  S.  Nat.  Mus.  Cat.  No.  15329c. 

The  specimens  represented  by  figures  3,  3a-b  were  figured  by  Walcott  [1886b,  PL  IX,  figs.  2,  2a-b,  respectively] 
as  Kutorgina  labradorica,  and  [1891a,  PI.  LXIX,  figs.  2,  2a-b,  respectively]  as  Kutorgina  labradorica  swantoneiisis. 

Figure  3c.  Longitudinal  section  of  a  ventral  valve  showing  the  presence  of  a  .short  iiseudodeltidium.  U.  S.  Nat. 
Mus.  Cat.  No.  1.5329d. 

The  specimens  represented  by  figures  3,  3a-c  are  all  from  Locality  25a,  Lower  Cambrian  limestones,  2  miles  east 
of  Swanton,  Franklin  County,  Vermont. 

Figures  3d,  3e,  and  3f.  Apical,  side,  and  posterior  views  of  a  specimen  preserving  the  area  and  pseudodeltidium. 
This  specimen  can  not  be  located.  The  drawing  was  labeled  as  having  been  made  from  a  specimen 
in  the  collections  of  the  American  Museum  of  Natural  History,  but  the  officials  inform  me  that  they 
have  no  record  of  such  a  specimen.     The  locality  is  unknown. 

MiCROMiTRA  (Paterina)  prospectensis  (Walcott)   (p.  352). 

Figure  4.  Apical  view  of  the  type  si>e(imen,  a  ventral  valve,  from  Locality  82,  Lower  Cambrian  sandy  shales,  summit 
of  Prospect  Mountain.  Eureka  district,  Nevada. 
4a.  Dorsal  valve  associated  with  the  ventral  ^■alve  represented  by  figure  4. 

The  specimens  represented  by  figures  4  and  4a  were  figured  by  Walcott  [1884b,  PI.  IX,  figs,  la  and  1.  respectively; 
1886b.  PI.  IX,  figs.  3  and  3a,  respectively;  and  1891a,  PI.  LXIX.  figs.  4  and  4a,  respectively]  as  Kutorgina  prospectensis. 
V.  S.  Nat.  Mus.  Cat.  Nos.  15335a  and  1.5335b,  respectively. 
10 


U.  S.   GEOLOGICAL  SURVEY 


MONOGRAPH   LI     PL.  II 


FRANCES  WieSER  DEL. 


MCLioTvpe  CO  BOSTON 


PLATE  IT.  11 

MiCROMITRA    ALABAMAENSIS    (Walcott)    (p.  337). 

Figure  5.  Apical  view  of  the  type  specimen,  a  rcimpressed  ventral  valve,  from  Locality  121,  Middle  Cambrian  Rogers- 
ville  shale,  4  miles  northeast  of  Rosjersville,  Tennessee.  V.  S.  Nat.  Mus.  Cat.  No.  51416a.  Speci- 
men figured  by  Walcott  [lS97b,  PI.  LIX,  fig.  5]  as  IphirJm  (ilahdmnetisis. 

5a.  Dorsal  valve  from  Locality  94a,  Middle  Cambrian  Conasauga  shale,  Coosa  \'alley,  Cherokee  County, 
Alabama.  U.  S.  Nat.  Mus.  Cat.  No.  56888a.  Specimen  figured  by  Walcott  [1897b,  PI.  LIX,  fig.  5a] 
as  Iphidea  alabamaensis. 

5b.  \'entral  valve  having  a  slight  median  depression,  from  Locality  14a,  Middle  Cambrian  Rogersville  shale, 
4  miles  north-northeast  of  Knoxville,  Knox  County,  Tennessee.     U.  S.  Nat.  Mus.  Cat.  No.  51413a. 

5c.  Outer  surface  of  .«hell  from  Locality  94,  Middle  Candjrian  Conasauga  shale,  Cowan  Creek  section,  Cherokee 
County,  Alabama,  enlarged  to  show  the  tendency  to  form  crenulations  in  the  striae.  U.  S.  Nat.  Mus. 
Cat.  No.  26432a.  This  bit  of  surface  was  figured  by  Walcott  [1897b,  PI.  LIX,  fig.  5b]  as  part  of  the 
surface  of  figure  5,  magnified;  it  is,  however,  taken  from  another  s]iecimen. 

MiCEOMiTRA   (Paterina)  logani  (Walcott)  ([).  350). 

Figures  6,  6a,  and  6b.  Apical,  side,  and  posterior  views  of  the  type  specimen,  from  Locality  2n,  Lower  Cambrian 
pebbles  in  conglomerate  at  Trois  Pistoles,  on  the  St.  Lawrence,  Province  of  Quebec,  Canada.  Coll. 
Geol.  Survey  Canada.  Specimen  figured  by  Walcott  [lS97b,  PI.  LIX,  figs.  2,  2a-b]  as  Iphidea  logani. 
In  the  Canadian  Survey  collections  it  was  labeled  as  the  type  of  '-Iphidea  bella  Billings."  (See 
pp.  345  and  3.50  and  figs.  1  and  Ic  of  this  plate.) 

MiCROMITRA  (Paterina)  supekba   (Walcott)  (p.  355). 

(Text  figs.  27A-B,  p.  35.5.) 
Figures  7,  7a,  and  7b.  Apical,  side,  and  posterior  views  of  the  type  specimen,  a  ventral  valve,  from  Locality  73a, 

Middle  Cambrian  sandy  "Tonto"  shale,  Chuar  Valley,  Grand  Canyon  of  the  Colorado,  Arizona. 

U.  S.  Nat.  Mus.  Cat.  No.  26429a.     Specimen  figured  by  Walcott  [1897b,  PI.  LIX,  figs,  la-c]  as  Iphidea 

superba. 
7c.  Specimen  of  the  dorsal  valve  associated  with  the  specimen  represented  by  figure  7.     L'.  S.  Nat.  Mus. 

Cat.  No.  26429b.     Specimen  figured  by  Walcott  [1897b,  PI.  LIX,  fig.  1]  as  Iphidea  superba. 
7d.  Nearly  perfect  dorsal  valve  from  Locality  74,  Middle  Cambrian  sandy  •'Tonto"  shale  at  head  of  Nunko- 

weap  Valley,  Grand  Canyon  of  the  Colorado,  Arizona.     U.  S.  Nat.  Mus.  Cat.  No.  51487a. 
7e.  Posterior  view  of   ventral  valve,  from  I>ocality  8j,    Middle  Cambrian  shale,  near  Gordon  Mountain, 

Ovando  quadrangle,  Montana,  showing  pseudodeltidium.     V.  S.  Nat.  Mus.  Cat.  No.  51488a. 
7f.  A  crushed  and  broken  ventral  valve,  associated  with  the  valve  represented  by  figure  7e,  showing  pseudo- 
deltidium.    U.  S.  Nat.  Mus.  Cat.  No.  5148Sb. 

MiCROMITRA  (Paterina)  labradorica  utahensis  (Walcott)  (p.  349). 

[Text  flg.  24,  p.  350.] 

Figures  8  and  8'.  Summit  and  side  A-iews  of  the  tyi>e  siiecimen,  a  ventral  valve  laterally  compressed.     V.  S.  Nat. 
Mus.  Cat.  No.  51431a. 
8a.  Posterior  half  of  a  ventral  valve  somewhat  distorted  by  compression.     V .  S.  Nat.  Mus.  Cat.  No.  51431b. 

The  specimens  represented  are  both  from  Locality  3d,  Middle  Cambrian,  Oquirrh  Range,  near  Ophir,  Utah. 

Wimanella  shelbtensis, Walcott   (p.  747). 

Figure  9.  Type  specimen,  the  ventral  valye,  flattened  in  the  shale.     Copied  from  Walcott  [1908d,  PI.  X,  fig.  3]. 
9a.  Interior  of  a  flattened  dorsal  valve. 

The  specimens  represented  are  both  from  Locality  17b,  Lower  Cambrian  Rome  (" Monte vallo")  formation,  4  miles 
south  of  Helena,  Shelby  County,  Alabama.     U.  S.  Nat.  Mus.  Cat.  Nos.  52272a  and  .52272b,  respectively. 

MiCROMITRA  (Paterina)  williaudi  Walcott   (p.  358). 

[Text  figs.  30A-E,  p.  3.58.1 
Figures  9b  and  9c.  Side  outlines  of  ventral  valves.     Drawn  from  casts  taken  in  a  natural  mold  from  Locality  17b, 
Lower  Cambrian  Rome  (''Montevallo  ")  formation,  4  miles  south  of  Helena,  Shelby  County,  -Vlabama. 
U.  S.  Nat.  Mus.  Cat.  Nos.  51481a  and  51481b,  respectively. 

MiCROMITRA  xisus  (Walcott)    (p.  338). 

Figure  10.  Exterior  of  type  specimen,  ventral  valve,  from  Locality  2r,  Lcnver  Cambrian,  2  miles  west  of  Bic,  Province 
of  Quebec,  Canada,  showing  radiating  ridges.     V.  S.  Nat.  Mus.  Cat.  No.  51440a. 

MiCROMITRA   (Paterina)  labradorica  orientalis  (Walcott)    (p.  348). 

Figure  11.  Exterior  of  type  specimen,  dorsal  valve,  from  Locality  C9,  Middle  Cambrian  limestone,  Kiulung  group, 
3  miles  southwest  of  Yenchuang,  Sintai  district,  Shantung,  China.    V.  S.  Nat.  Mus.  Cat.  No.  52516a. 


PLATE    III. 


13 


PLATE  III. 
MiCROMiTRA  (Paterina)  stissingensis  (Dwight)   (p.  353). 

FiGtJRE  1.  Apioal  view  of  the  type  specimen,  a  ventral  valve.     U.  S.  Nat.  Mus.  Cat.  No.  .51484a.     Specimen  figured 

by  Dwight  [1889,  PI.  VI,  tip;.  G]  as  Kulorgina  stissingensU. 
la.  Dorsal  valve,  flattened  in  the  shale.     U.  S.  Nat.  Mus.  Cat.  No.  51484b.     The  rear  view  of  this  specimen 

was  given  by  Dwight  [1889,  PI.  VI,  fig.  8]. 
lb.  Apical  \dew  of  a  cast  in  limestone  of  a  ventral  valve.     U.  S.  Nat.  Mus.  Cat.  No.  .51484c. 
Ic.  Interior  of  a  typical  specimen  of  a  compressed  dorsal  valve.     V .  S.  Nat.  Mus.  Cat  No.  51484d.     Specimen 

figured  by  Dwight  [1889,  PI.  VI,  fig.  5]  as  Kutorgina  stissingensis. 
Id.  Posterior  view  of  a  compressed  ventral  valve  that  shows  the  area  of  a  narrow  pseud odeltidium. 

The  specimens  represented   by  figures   1,  la-d  are  from  Locality  367d,  Middle  Cambrian,  vicinity  of  Stissing, 
Dutchess  County,  New  York. 

Figure  le.  Specimen  doubtfully  referred  to  this  species  from  Locality  14s,  Middle  Cambrian,  Ogygopsis  zone.  Mount 
Stephen,  British  Columbia.     U.  S.  Nat.  Mus.  Cat.  No.  ol483a. 

MiCROMiTKA  pusiLLA   (LinQarsson)   (p.  339). 

Figures  2  and  2a.  Apical  and  posterior  views  of  a  ventral  valve.    U.  S.  Nat.  Mus.  Cat.  No.  ol478a. 
2b  and  2b'.  Top  and  side  views  of  a  ventral  valve.     U.  S.  Nat.  Mus.  Cat.  No.  5147Sb. 
2c.  Exterior  of  a  dorsal  valve.    U.  S.  Nat.  Mus.  Cat.  No.  .51478c. 

The  specimens  represented  are  all  from  Locality  8w,  Middle  Cambrian  limestones  near  Andraruni,  Sweden. 
MiCROMITRA    PEALEI    (Walcott)     (p.  339). 

Figures  3,  3a,  and  3b.  Apical,  side,  and  posterior  views  of  the  type  specimen,  from  Locality  155a,  Middle  Cambrian 

limestone  near  Hillsdale,  Montana.     U.  S.  Nat.  Mus.  Cat.  No.  26430a.     Specimen  figured  by  Walcott 

[1897b,  PI.  LIX.  figs.  3,  3a-b]  iis  Iphidea  pealei. 
3c.  Dorsal  valve  from  the  same  bed  of  limestone  as  the  ventral  valve  re])resented  by  figure  3.     U.  S.  Nat. 

Mus.  Cat.  No.  26430b.      Specimen  figured  by  Walcott  [1897b.  PI.  LIX,  fig.  3c]  as  Iphidea  pealei. 
3d.  Ventral  valve  with  strong  radiating  ridges,  from  Locality  159,  Middle  Cambrian  limestone,  north  of  West 

Gallatin  (Gallatin)  River,  Montana.     U.  S.  Nat.  Mus.  Cat.  No.  51471a, 
3e  and  3e'.  Top  and  back  views  of  a  transverse  dorsal  valve  with  strong  radiating  ridges,  from  Locality  5f, 

Middle  Cambrian  limestone,  12  miles  south  of  Neihart,  Montana.     V.  S.  Nat.  Mus.  Cat.  No.  51470a. 

MiCROMITRA  (Paterina)  crenistria  (Walcott)   (p.  345). 

Figures  4,  4a,  and  4b.  Apical,  side,  and  posterior  vifews  of  the  type  specimen,  from  Locality  74,  Middle  Cambrian 
limestone,  Tonto  group,  near  the  head  of  Nunkoweap  A'alley,  Grand  Canyon  of  the  Colorado,  .Vrizona. 
U.  S.  Nat.  Mus.  Cat.  No.  26431a.  Specimen  figured  by  Walcott  [lS97"b,  PI.  LIX,  figs.  4,  4a-b]  as 
Iphidea  crenistria. 

MiCROMITRA   SCLT-PTILIS    (^leek)    (p.  341). 

Figures  5,  5',  and  5".  Apical,  side,  and  posterior  views  of  the  type  specimen,  from  Locality  302,  Middle  Cambrian 
limestone  east  of  West  Gallatin  (Gallatin)  River,  Montana.  U.  S.  Nat.  Mus.  Cat.  No.  7864a.  Speci- 
men figured  by  Walcott  [1884b,  PI.  I,  figs.  7,  7a]  as  Kutorgina  sculplilis. 

5a,  5a',  and  5a".  Top,  side,  and  back  views  of  a  ventral  valve  from  Locality  302b,  Middle  Cambrian  lime- 
stones near  Crowfoot  Ridge,  Yellowstone  National  Park,  Wyoming.  U.  S.  Nat.  Mus.  Cat.  No.  35212a. 
Specimen  figured  by  Walcott  [1S99,  ?1.  I.X,  figs.  5,  5a-c].  A  portion  of  its  surface  is  enlarged  in 
figure  5e. 

5b.  Dorsal  valve  from  Locality  58,  Middle  Cambrian  Secret  Canyon  shale,  Eureka  di.«trict,  Nevada.  U.  S. 
Nsit.  .Mus.  Cat.  No.  24.551a.  Specimen  figured  by  Hall  and  Whitfield  [1S77,  PI.  1.  fig.  1 1]  as  Kutorgina 
minutissima;  and  by  Walcott  |18S4b,  PL  I,  fig.  7b]  as  Kutorgina  sculplilis. 

5c.  Dorsal  valve  associated  with  the  shell  represented  by  fig.  ob.     U.  S.  Nat.  Mus.  Cat.  No.  245.Tlb.     Specimen 
figured  by  Hall  and  Whitfield  [1877,  PL  I,  fig.  12]  as  Kutorgina  minutissima;  and  by  Walcott  [1884b, 
PL  IX,  fig.  7]  as  Kutorgina  sculplilis. 
14 


U.  S.   GEOLOGICAL  SURVEY 


MONOGRAPH   LI     PL.  Ill 


FRANCES  WIESER  DEL. 


MELIOTVPe    CO   BOSTON 


PLATE  III.  15 

MiCROMiTRA  SCT7LPTILIS  (Meek) — Continued. 

Figure    5d.  Crushed  ventral  valve  from  Locality  8i,  Middle  Cambrian  shaly  Marjum  limestone  near  Antelope  Springs, 
House  Range,  Utah.     U.  S.  Nat.  Mus.  Cat.  No.  51494a. 
5e.  A  portion  of  the  surface  of  the  specimen  represented  by  figure  5a,  greatly  enlarged.     U.  S.  Nat.  Mus. 
Cat.  No.  35212a. 

MicROMiTRA  (Iphidella)  ornatella   (Linnarsson)   (p.  360). 

Figures  (i,  6a,  and  Gb.  Apical,  side,  and  posterior  views  of  a  typical  specimen  from  Locality  320f,  Middle  Cambrian 

limestone  at  Andrarum,  Sweden.     U.  S.  Nat.  Mus.  Cat.  No.  26667a. 
6c.  Dorsal  valve  from  Locality  8w,  Middle  Cambrian  limestone  near  Andrarum,  Sweden.     U.  S.  Nat.  Mus. 

Cat.  No.  51460a. 
6d.  Interior  of  a  dorsal  valve  from  Locality  16h,  Middle  Cambrian  shale  at  Borregaard,  Bornholm,  Denmark. 

U.  S.  Nat.  Mus.  Cat.  No.  51490a. 

MiCROMiTRA  sjj.  limit.  (Walcott)   (p.  343). 

Figure  7.  Dorsal  valve  from  Locality  302b,  Middle  Cambrian  limestones  near  Crowfoot  Ridge,  Yellowstone  National 
Park,  Wyoming.  U.  S.  Nat.  Mus.  Cat.  No.  51509a.  Specimen  figured  by  Walcott  [1899,  PI.  LX, 
fig.  6]  as  "Iphidea,  sp.  undet." 

MiCROMiTRA   (Paterina)  phillipsi   (IIoll)    (p.  351). 

Figure  8.  Top  view  of  dorsal  valve  and  side  outline  of  valves  from  Locality  304g,  Upper  Cambrian  Hollybush  sand- 
stones, Malvern  Hills,  England.  Copied  from  Davidson  [1866,  PI.  IV,  figs.  17a  and  17c];  Davidson's 
figures  were  drawn  from  the  type  specimen  illustrated  by  Holl  [1865,  p.  102,  figs.  10b  and  10c]. 

MiCROMiTRA  (Iphidella)  nyssa  Walcott  (p.  360). 

Figure  9.  Top  view  of  type  specimen,  a  ventral  valve.     Copied  from  Walcott  [1908d,  PI.  VII,  fig.  5]. 
9a.  Top  view  of  dorsal  valve. 

The  specimens  represented  are  both  from  Locality  4q,  Middle  Cambrian  shale,  near  Gordon  Mountain,  Ovando 
quadrangle,  Montana.     U.  S.  Nat.  Mus.  Cat.  Nos.  51441a  and  51441b,  respectively. 

MiCROMiTRA  (Paterina)  etheridgei  (Tate)   (p.  346). 

Figure  10.  Top  view  of  type  specimen,  a  ventral  valve  from  Locality  315,  Middle  Cambrian  at  Curramulka,  South 
Australia.  Original  in  the  collection  of  the  LTniversity  of  Adelaide,  South  .\ustralia;  cast  in  the  Ignited 
States  National  Museum  (Cat.  No.  58301).  Specimen  figured  by  Tate  [1892,  PI.  II,  figs.  7a-c]  as 
Platyceras  etheridgei. 

10a  and  10b.  Side  and  back  ^dews  of  ventral  valve  represented  in  figure  10.  Original  in  the  collection  of 
the  University  of  Adelaide;  cast  in  the  United  States  National  Museum  (Cat.  No.  58301). 

10c.  Back  view  of  another  ventral  valve  from  the  same  locality  as  the  valve  represented  by  figure  10.  Original 
in  the  collection  of  the  L'niversity  of  Adelaide;  cast  in  the  United  States  National  Museum  (Cat.  No. 
58302). 


PLATE    IV 


62667°— VOL  51,  pt  2—12 2  17 


PLATE  IV. 
MiCROMiTKA  (Iphidella)  pannula   (Wliite)   (p.  361). 

(Text  fig.  32,  p.  362,  and  PI.  IV,  figs.  3  and  3a. ] 

Figures  1  and  la.  Apical  and  side  views  of  a  ventral  valve  from  Locality  74,  Middle  Cambrian  "Tonto"  sandstone 

Grand  Canyon  of  the  Ctilorado,  Arizona.     U.  S.  Nat.  Mus.  Cat.  No.  51446a. 
lb.  Dorsal  valve  from  Locality  149a,  Middle  Cambrian  limestone  on  Pole  Creek,  Madi.s<in  County,  Montana. 

U.  S.  Nat.  Mus.  Cat.  No.  5144.5b. 
Ic.  Dorsal  valve  from  Locality  14,  Middle  Cambrian  limestone  7  miles  southwest  of  Rome,  Floyd  County, 

Georgia.     U.  S.  Nat.  Mus.  Cat.  No.  51444c. 
Id  and  le.  Posterior  and  side  views  of  ventral  valve  from  Locality  30,  Lower  Cambrian  limestones  near 

Pioche,  Nevada.     U.  S.  Nat.  Mus.  Cat.  No.  514.52a.     Copied   from   Walcott  [1908c,   PI.   I,   figs,   lb 

and  la,  respectively.]    The  figures  were  there  wrongly  placed  as  the  posterior  and  side  views  of  the 

specimen  represented  by  figure  Ir  of  this  plate.     The  latter  specimen  occurs  in  British  Columbia; 

the  one  represented  by  figures  Id  and  le  occurs  in  Nevada. 
If.  Posterior  view  of  the  dorsal  valve  represented  in  figure  lb,  showing  the  characters  described  in  the  text 

(see  p.  362).     U.  S.  Nat.  Mus.  Cat.  No.  51445b. 
Ig.  Drawing  of  the  type  specimen  of  the  species.     Locality  31a,  Lower  Cambrian  siliceous  shale  near  Pioche, 

Nevada.     U.  S.  Nat.  Mus.  Cat.  No.  1.5331a.     Specimen  figured  by  White  [1877,  PI.  I,  figs.  4a  and  4b] 

as  Trematk  pannula;  and  by  Walcott  [ISSGb,  PL  VII,  figs.  3  and  3a;  and  lS91a,  PI.  LXIX,  fig.  5d]  as 

Kutorgina  pannula.     The  surface  is  enlarged  in  figure  lo  of  this  plate. 
Ih  and  li.  Apical  and  posterior  views  of  a  dorsal  (?)  valve  from  Locality  73a,  Middle  Cambrian  "Tonto" 

sandstone,  Grand  Canyon  of  the  Colorado,  Arizona.     U.  S.  Nat.  Mus.  Cat.  No.  51447a.     The  surface 

is  enlarged  in  figure  In  of  this  plate. 
Ij  and  1  1.  Apical  and  side  views  of  a  small  specimen  from  Locality  31a,  Lower  Cambrian  limestone  near 

Pioche,  Nevada.     U.  S.  Nat.  Mus.  Cat.  No.  15333a.     Specimen  figured  by  Walcott  [188(ib,  PI.  VIII, 

figs.  2  and  2a;  1801a,  PI.  LXIX,  figs.  5  and  5a]  as  Kutorgina  pannula. 
Ik.  Dorsal  valve  from  same  locality  as  the  specimens  represented  by  figures  Ij  and  1  1.     U.  S,  Nat.  Mus. 

Cat.  No.  15333b.     Specimen  figured  by  Walcott  [1886b,  PI.  VIII,  figs.  2b  and  2c;  1887,  PI.  I,  fig.  14b; 

and  1891a,  PI.  LXIX,  figs.  5b  and  5e]  as  Kutorgina  pannula.     The  outer  surface  is  enlarged  in  figure 

Ip  of  this  plate. 
Im.  Ventral  valve  from  Locality  38a,  Lower  Cambrian  limestones  near  North  Granville,  Washington  County, 

New  York.     U.  S.  Nat.  Mus.  Cat.  No.  17442a.     Specimen  figured  by  Walcott  [1887,  PI.  I,  figs.  14  and 

14a;  and  1891a,  PI.  LXIX,  figs.  5c  and  5f]  as  Kutorgina  pannula.     The  outer  surface  is  enlarged  in 

figure  Iq  of  this  plate. 
In.  Enlargement  of  a  portion  of  the  outer  surface  orthe  specimen  represented  by  figure  Ih. 
lo.  Enlargement  of  a  portion  of  the  outer  surface  of  the  type  specimen,  figure  Ig. 
Ip.  Enlargement  of  a  portion  of  the  outer  surface  of  the  specimen  repre.«ente<l  by  figure  Ik.     Figured  by 

Walcott  [1891a,  PI.  LXIX,  fig.  5e]  as  the  surface  of  the  specimen  represented  by  figure  Im;  and 

[1887,  PI.  I,  fig.  14b;  and  1886b,  PI.  VIII,  fig.  2c]  as  the  outer  surface  of  Ik. 
Iq.  Enlargement  of  a  portion  of  the  outer  surface  of  the  dorsal  valve  represented  by  figure  Im.     Figured  by 

Walcott  [1891a,  PI.  LXIX,  fig.  5f]  as  the  surface  of  the  valve  represented  by  figure  Ik;  and  [1887,  PL 

I,  fig.  14a]  as  the  outer  surface  of  Im. 
Ir.  Ventral  valve  from  Locality  14s,  Middle  Cambrian  Ogygopsis  zone  on  Mount  Stephen,  British  Columbia. 

Coll.  Mr.  Byron  E.  Walker,  Toronto,  Canada.     Copied  from  Walcott  [1908c,  PI.  I,  fig.  1];  see  note 

under  figures  Id  and  le. 
Is.  Enlargement  by  photography  of  a  ventral  valve  from  Locality  74,  Middle  Cambrian  ".Tonto"  sandstone. 

Grand  Canyon  of  the  Colorado,  Arizona.     U.  S.  Nat.  Mus.  Cat.  No.  51446b. 
It.  Enlargement  by  photography  of  a  ventral  valve  from  Locality  149a,  Middle  Cambrian  limestones  on  Pole 

Creek,  Madison  County.  Montana.     IT.  S.  Nat.  Mus.  Cat.  No.  51445a. 

MiCROMITRA    (IpHIDET.LA)    PANNIILA    MALADENSIS    (Walcott)     (p.  364). 

Figure  2.  Exterior  of  ventral  valve  from  Locality  Sb,  Middle  Cambrian  limestone,  2  miles  southeast  of  Malade,  Idaho, 
showing  pitting  of  surface,  and  obscure,  radiating  ridges.     IT.  S.  Nat.  Mus.  Cat.  No.  51468a. 
2a.  Apical  view  of  ventral  valve  associated  with  valve  represented  by  figure  2.    U.  S.  Nat.  Mus.  Cat.  No. 
51468b. 
18 


U.   S.   GEOLOGICAL  SURVEY 


MONOGRAPH   LI     PL.    IV 


MELioTvpe  CO  ecsTOH 


PLATE  IV.  19 

MiCROMITRA    (IpIIIDELLA)    PANNULA    MALADENSIS    (Walcott) C07)tilHl('(l. 

Figures  2a'  and  2a".  Side  aud  back  viows  of  specimen  represented  by  figure  2a,  illustrating  the  area  and  pseudodel- 
tidium. 

2b,  2b',  and  2b".  Apical,  back,  and  side  views  of  an  elevated  ventral  valve  from  Locality  6g,  Middle  Cam- 
brian limestone,  Chappie  Arm,  Trinity  Bay,  Newfoundland.     U.  S.  Nat.  Mus.  Cat.  No.  51496a. 

2c.  Apical  view  of  an  elevated,  laterally  compressed  ventral  valve  associated  with  the  valve  represented  by 
figure  2b.     U.  S.  Nat.  Mus.  Cat.  No.  51469b. 

2d  and  2e.  E,\terior  of  two  dorsal  valves  from  Locality  5b,  Middle  Cambrian  limestone,  2  miles  southeast  of 
Malade,  Idaho,  with  the  same  type  of  surface  as  the  specimen  rcjirescnted  by  figure  2.  U.  S.  Nat. 
Mus.  Cat.  Nos.  51468c  and  5146Sd,  respectively.     Figure  2e  represents  the  type  specimen. 

2f.  Partly  exfoliated,  transverse  dorsal  valve  from  locality  6g,  Middle  Cambrian  limestone,  Chappie  Arm, 
Trinity  Bay,  Newfoundland.     U.  S.  Nat.  Mus.  Cat.  No.  51469c. 

2g.  Enlargement  of  a  portion  of  the  surface  near  the  center  of  a  ventral  valve  from  Locality  61),  Middle  Cam- 
brian limestone,  2  miles  southeast  of  Malade,  Idaho,  that  has  (on  its  frontal  portion)  a  surface  like 
that  represented  by  figure  4c  of  the  variety  ophirensis.     U.  S.  Nat.  Mus.  Cat.  No.  51468e. 

MiCROMITRA    (IpIIIDELLA)    PANNULA    (White)     (|).  Sfil). 
(Text  fig.  32,  p.  302,  and  PI.  IV,  figs.  1,  la-t.] 

Figure  3.  Posterior  portion  of  a  ventral  valve  having  a  very  fine  surface  of  the  type  represented  by  figure  Iq. 

3a  and  3a'.  Apical  and  side  views  of  a  ventral  valve  associated  with  the  specimen  represented  by  figure  3. 

The  specimens  represented  are  both  from  Locality  14,  Middle  Cambrian  limestone,  7  miles  southwest  of  Rome, 
Floyd  County,  Georgia.     U.  S.  Nat.  Mus.  Cat.  Nos.  51444a  and  51444b,  respectively. 

MiCROMITRA    (IPIIIDELLA )    PANNULA    OPHIRENSIS    (Walfott)    (p.  .365). 

Figures  4  and  4'.     Apical  and  side  views  of  a  ventral  valve.     V.  S.  Nat.  Mus.  Cat.  No.  51464a. 

4a,  4a',  and  4a".  Apical,  back,  and  side  views  of  a  ventral  valve,  the  type  specimen,  in  which  the  beak 
slightly  overhangs  the  posterior  margin.     U.  S.  Nat.  Mus.  Cat.  No.  51464b.     (See  fig.  4c.) 

4b.  Exterior  of  a  dorsal  valve  with  very  fine,  undulating,  concentric  striae.     U.  S.  Nat.  Mus.  Cat.  No.  51464c. 

4c.  Enlargement  of  a  portion  of  the  specimen  represented  by  figure  4a,  to  illustrate  irregular  and. inoscu- 
lating stria;.     U.  S.  Nat.  Mus.  Cat.  No.  51464b. 

4d  and  4d'.  Top  and  back  views  of  a  transverse  dorsal  valve.     U.  S.  Nat.  Mus.  Cat.  No.  51464d. 

4e.  Partly  exfoliated  dorsal  valve,  showing  the  cast  of  a  median  septum  and  the  position  of  the  central 
muscle  scars.     U.  S.  Nat.  Mus.  Cat.  No.  51464e. 

4f.  A  small,  convex  dorsal  valve.     U.  S.  Nat.  Mus.  Cat.  No.  51464f. 

The  specimens  represented  are  all  from  Locality  3e,  Middle  Cambrian  limestone,  Oc{uirrh  Range,  near  Ophir,  Utah. 


PLATE   V. 


21 


PLATE  V. 

a.  Pseudo-area.  p.  Pedicle  opening, 

h.  Central  mascle  scar.  s.  Median  septum, 

j.  Anterior  lateral  muscle  scar.  v.  Visceral  area. 

vs.  Main  vascular  sinus. 

KuTORGiNA  ciNGULATA   (BilHngs)  (p.  580). 

(Text  figs.  3,  p.  299,  8,  p.  29!l,  and  .WA-C,  p.  581.) 

Figure  1.  Top  and  side  \-iew  of  a  partly  exfoliated  vontral  valve  from  Locality  25a,  liower  Cambrian  limestone,  2 

miles  ea.st  of  Swanton,  Vermont.     U.  S.  Nat.  Mu.s.  ('at.  No.  15:i37a.     Speeimeii  figured  by  Waleott 

[188eb,  PI.  IX,  fig.  Id;  and  1891a,  PI.  LXIX,  fig.  Id], 
la.  Side  view  of  the  two  valves  united,  from  Locality  25a,  near  Swanton,  Vermont.     U.  S.  Nat.  Mus.  Cat.  No. 

15337b.     Specimen  figured  by  Walcolt  [1886b,  PI.  IX,  fig.  Ic;  and  1891a,  PI.  LXIX,  fig.  Ic]. 
lb   Ic,  and  Id.  Side,  ventral,  and  dorsal  \-iews  of  a  nearly  entire  shell,  natural  size,  from  Locality  26a,  near 

Swanton,  Vermont.     U.  S.  Nat.  Mus.  Cat.  No.  15337d.     Specimen  figured  by  Waleott  f  188Gb,  PI.  IX, 

figs.  1,  la-b;  and  1891a,  PI.  LXIX,  figs.  1,  la-b]. 
le  and  If.  Side  and  dorsal  \'iews  of  a  younger  shell  than  that  represented  by  figures  lb,  Ic,  and  Id,  but  from 

the  same  locality.     V.  S.  Nat.  Mus.  Cat.  No.  15336a. 
Ig.  E.xfoliated  dorsal  valvii,  showing  central  muscle  scars  and  radiating  vascular  canals.     From  Locality 

392a,  Lower  Cambrian  limestones  at  L'Anse  au  Loup,  Labrador.     L".  S.  Nat.  Mus.  Cat.  No.  14893a. 
Ih.  Interior  of  a  dorsal  valve  from  Locality  25a,  Lower  Cambrian  limestone,  2  miles  east  of  Swanton,  Vermont, 

showing  muscle  scars  and  vascular  canals.     V.  S.  Nat.  Mus.  Cat.  No.  15337c.     Specimen  figured  by 

Waleott  [1886b,  PI.  IX,  fig.  If;  and  1891a,  PI.  LXIX,  fig.  If]. 
li.  Exterior  of  a  dorsal  valve  from  Locality  26a,  Lower  Cambrian,  2  miles  east  of  Swanton,  Vermont.     U.  S. 

Nat.  Mus.  Cat.  No.  15337f.     Specimen  figured  by  Waleott  [1886b,  PI.  IX,  fig.  le;  and  1891a,  PI.  LXIX, 

fig.  le]. 
Ij.  Exterior  and  side  views  of  a  fine  ventral  valve  from  Locality  2o,  Lower  Cambrian  limestone,  Bic  Harbor, 

Pro\-ince  of  Quebec,  Canada.     U.  S.  Nat.  Mus.  Cat.  No.  51510a. 
Ik  and  Ik'.  View  of  area  and  side  view  of  a  ventral  valve  from  Bic  Harbor  (Locality  2o).     U.  S.  Nat.  Mus. 

Cat.  No.  51510b. 
11  and  Im.  Exterior  views  of  two  dor.sal  valves  from  Bic  Harbor  (Locality  2o).     U.  S.  Nat.  Mus.  Cat.  Nos. 

51510c  and  51510d,  respectively. 
In.  Xiow  of  pseudo-area  beneath  apex  of  an  elevated  ventral  valve  from  Locality  25a,  Lower  Cambrian  lime- 
stone, 2  miles  east  of  Swanton,  Vermont.     U.  S.  Nat.  Mus.  Cat.  No.  15336b. 
lo.  Transverse  section  of  the  two  ^•alves  in  natural  position,  from  Swanton,  Vermont  ( Locality  25a).     The  gaping 

pedicle  opening  is  well  shown.     L'.  S.  Nat.  Mus.  Cat.  No.  15336c. 
Ip.  Enlargement  of  a  cross  section  of  a  fragment  of  the  shell  from  Locality  25a,  Swanton,  Vermont.     V.  S. 

Nat.  Mus.  Cat.  No.  15337e. 
Iq.  Enlargement  of  a  longitudinal  section  of  the  shell  at  the  apex  of  the  ventral  valve.     Locality  25a,  Lower 

Cambrian,  2  miles  east  of  Swanton,  Vermont.     I'.  S.  Nat.  Mus.  Cat.  No.  15336d. 
Ir  and  Is.  Exterior  of  ventral  and  dorsal  valves  from  Locality  392a,  Lower  Cambrian  limestone  at  L'Anse 

au  Loup,  Straits  of  BcUeisle,  Labrador,  Canada.     V.  S.  Nat.  Mus.  Cat.  Nos.  14893b  and  14893c, 

respectively. 

KUTORGINA  PECULIAKIS  (Tate)  (p.  583). 

Figure  2.  Top  view  of  type  specimen,  a  dorsal  valve,  from  Locality  316a,  Middle  ?  Cambrian,  at  Ardrossan,  Yorke 
Peninsula,  South  Australia.  Original  in  the  collection  of  the  University  of  Adelaide,  Adelaide, 
South  Australia.  Cast  in  the  United  States  National  Museum  (Cat.  No.  58300).  Specimen  figiured 
by  Tate  [1892,  PI.  II,  fig.  5]  as  Orlhis  (.?)  peculiaris. 

KUTORGINA    PERUGATA    Walcott    (p.  583). 

Figure  3.  Exterior  and  side  view  of  an  exfoliated  ventral  valv<'.     I'.  S.  Nat.  Mus.  Cat.  No.  51511a.     The  outline  of 
the  visceral  area  is  dra^vn  from  another  specimen.     V.  S.  Nat.  Mus.  Cat.  No.  51511g. 
3a.  Top  and  side  views  of  a  less  elongate  ventral  valve  than  that  represented  by  figure  3.     V.  S.  Nat.  Mus. 

Cat.  No.  51511b. 
22 


U.  S.   GEOLOGICAL  SURVEY 


MONOGRAPH   U     PL.  V 


f'RANCeS  W1ESER  DEL 


liQTV^E:    CO    BOSTON 


PLATE  V.  ■  23 

KuTORGiNA  PERUGATA  Walcott — Continued. 

Figure  3b.  Exterior,  side,  and  back  views  of  a  dorsal  valve.     The  pseudo-area  is  broken  away.     U.  S.  Nat.  Mus. 

Cat.  No.  51511c. 
3c.  Top,  back,  and  side  views  of  an  exfoliated  dorsal  valve,  the  type  specimen,  showing  pseudo-area.     U.  S. 

Nat.  Mus.  Cat.  No.  51511d. 
3d.  Exterior  of  dorsal  valve  illustrating  variation  in  the  concentric  corrugations.     U.  S.  Nat.  Mus.  Cat.  No. 

51511e. 
3e.  Small,  strongly  corrugated  ventral  valve,  drawn  from  the  cast  of  a  natural  mold.     U.  S.  Nat.  Mus.  Cat. 

No.  51511f. 

The  specimens  represented  are  all  from  Locality  Iv,  Lower  Cambrian,  Silver  Peak  quadrangle  (U.  S.  Geol.  Sur- 
vey), Nevada. 

KUTOEGINA    SARDINIAENSIS    Walcott   (p.  584). 

Figure  4.  Ventral  valve,  the  type  specimen,  from  Locality  354e,  Middle  ?  Cambrian,  Sardinia.     Copied  from  Borne- 

mann  [1891,  PI.  XIX,  fig.  21],  who  de.s<-ribes  and  figures  the  specimen  as  Lingula  roualli. 
4a.  Exterior  of  ventral  valve  from  Locality  354e,  Middle  ?  Cambrian  shale  at  Porto  Canal  Grande,  Sardinia. 

U.  S.  Nat.  Mus.  Cat.  No.  18301a.  " 
4b  and  4c.  Exteriors  of  dorsal  valves  from  Locality  3S4e,  Middle  ?  Cambrian,  Sardinia.     Copied  from  Borne- 

mann  [1891,  PI.  XIX,  figs.  22  and  23,  respectively],  who  describes  and  figures  them  as  Kutorgina 

cingtdata. 

Kutorgina  granulata  Matthew  (p.  582). 

Figures  5  and  5a.  Top  and  side  views  of  a  broken  ventral  valve.     Type  specimen  figured  l)y  Matthew  [1899a, 

PL  I,  fig.  2a];  it  is  redrawn  on  this  plate. 
5b.  Partly  exf(jliated  interior  of  a  dor.sal  valve.     Specimen  figured  by  Matthew  [1899a,  PL  I,  fig.  2c];  it  is 

redrawn  on  this  plate. 
5c.  Partly  exfoliated  exterior  of  a  dorsal  valve.     Specimen  figured  by  Matthew  [lS99a,  PI.  I,  fig.  2b];  it  is 

redrawai  on  this  plate. 

The  specimens  represented  are  all  from  Locality  314b,  Lower  Cambrian  limestone.  Smith  Sound,  Newfoundland, 
and  are  in  the  collection  of  the  University  of  Toronto,  Canada. 


PLATE    VI. 


25 


PLATE  VI. 

MiCKWiTZiA  MONiLiFERA   (Liiinarsson)  (p.  330). 

[PI.  LIX,  Ug.  2.] 

Figures  J,  1',  and  1".     Top,  side,  and  back  views  of  a  partly  exfoliated  ventral  valve.     U.  S.  Nat.  Miis.  Cat.  No. 

51520a. 
la.  Top  and  side  views  of  a  small  ventral  valve.     U.  S.  Nat.  Mus,  Cat.  No.  51520b. 
lb.  Exfoliated  dorsal  valve.     U.  S.  Nat.  Mus.  Cat.  No.  51520c. 
Ic.  Interior  of  a  dorsal  valve.     V.  S.  Nat.  Mus.  Cat.  No.  51520d. 
Id.  Interior  of  a  dorsal  valve,  showing  a  trace  of  the  path  of  advance  of  the  posterior  lateral  muscle  scars. 

U.  S.  Nat.  Mus.  Cat.  No.  51520e. 
le.  Posterior  view  of  a  dorsal  valve,  showing  the  arching  of  the  margin.     The  apex  of  the  valve  Ls  broken  away. 

U.  S.  Nat.  Mus.  Cat.  No.  51520f. 
If.  Interior  of  a  worn  dorsal  valve,  showing  indications  of  a  median  depression  and  the  path  of  advance  of  the 

posterior  lateral  scars.     U.  S.  Nat.  Mus.  Cat.  No.  51520g. 
Ig,  Ih,  li,  and  Ij.  Ventral,  dorsal,  side,  and  back  views  of  a  cast  of  the  two  valves,  the  dorsal  valve  having 

been  crushed  inward.     U.  S.  Nat.  Mus.  Cat.  No.  23893a. 
Ik.  Surface  of  an  inner  lamellation  or  layer  of  shell  magnified  six  times.     U.  S.  Nat.  Mus.  Cat.  No.  51520h. 
1 1.  Surface  of  an  inner  layer  of  shell  magnified  about  five  times.     This  is  a  character  illustrated  by  Linnarsson 

[1896b,  PI.  XI,  fig.  2].     U.  S.  Nat.  Mus.  Cat.  No.  515201. 
Im.  Exterior  layer  of  shell,  partly  worn  so  as  to  show  sections  of  the  papilla^  and  punctte.     The  papillae 

when  unworn  are  elevated  and  have  a  minute  opening  at  the  apex  (see  fig.  In).   U.  S.  Nat.  Mus.  Cat. 

No.  51520J. 
In.  Exterior  papillose  surface  of  a  shell,  greatly  magnified.     U.  S.  Nat.  Mus.  Cat.  No.  51520k. 

The  specimens  represented  by  figures  1,  la-n  are  all  from  Locality  390j,  Lower  Cambrian  Eophyton  sandstone  at 
Lugnas,  Province  of  Skaraborg,  Sweden. 

Figures  lo  and  Ip.  Side  and  back  views  of  a  cast  of  a  compressed  and  somewhat  distorted  ventral  valve  from 
Locality  396r,  Lower  Cambrian,  at  Streitberg,  near  Reval.  Esthonia,  Russia.  Copied  from  Schmidt, 
1888,  PI.  II,  figures  12c  and  12d,  respectively. 

MicKwiTZiA  PRETiosA  Walcott  (p.  332). 

Figure  2.  Top  view  of  the  type  specimen  from  Locality  390j,  Lower  Cambrian  Eophyton  sandstone  at  LugnSs.  Province 
of  Skaraborg,  Sweden.  U.  S.  Nat.  Mus.  Cat.  No.  51523a.  Copied  from  Walcott  [1908d,  PI.  VII, 
fig.  2]. 

MicKwiTZiA  FORMOSA  (Wimaii)  (p.  329). 

Figures  3,  3a,  and  3b.  Top,  side,  and  posterior  views  of  the  type  specimen  from  Locality  3H1,  Middle?  Cambrian, 
sandstone  on  the  peninsula  of  Biludden,  Gofle  Bay,  Sweden.     Original  in  the  collection  of  the  Univer- 
sity of  L^psala;  cast  in  the  L'nited  States  National  Museum  (Cat.  No.  58299). 
3c.  Enlargement  of  a  portion  of  the  surface  of  one  of  the  inner  layers  of  the  shell  represented  in  figure  3,  the 
epidermal  layer  having  iirobably  been  exfoliated. 

The  specimen  represented  was  figured  by  "\\'iman  [1902,  PI.  II,  figs.  1-5]  as  Causea  formosa . 

MiCKMiTziA  occiDENs  Walcott  (p.  331). 

Figure  4.  Type  specimen,  from  Localily  174c,  Lower  Cambrian  shale.  Silver  Peak  quadrangle  (U.  S.  Geol.  Survey), 
Nevada,  showing  outer  and  inner  surfaces  of  the  outer  layer.     IT.  S.  Nat.  Mus.  Cat.  No.  51518a. 
4'.  Side  outline  of  specimen  represented  by  figure  4. 

Figures  4  and  4'  are  copied  from  Walcott  [190Sd,  PL  VII,  fig.'*.  1  and  1']. 
26 


U.  S.  GEOLOGICAL  SURVEY 


MONOGRAPH    LI      PL.  VI 


PftANCES  WIESER  OEt 


LiOTvPE  CO  Boston 


PLATE   VII. 


27 


PLATE  VII. 


Central  lateral  spat-e  of  area. 
Outer  lateral  space  of  area. 
Flexure  line  of  area, 
rmbonal  muscle  scar. 
Central  muscle  scar. 
Transmedian  muscle  scar. 
Anterior  lateral  muscle  scar. 


k.  Middle  lateral  muscle  scar. 
1.  Outside  lateral  muscle  scar, 
p.  Pedicle  groove, 
vs.  Main  vascular  sinus. 
X.  Heart-shaped  cavity. 
x'.  A  slight  depression  of  the  bottom  of  the 
heart-shaped  cavity. 


Obolus  apollinis  Eichwald  (p.  381  J. 

[Text  figs.  4,  p.  299,  and  15.  p.  299,  and  PI.  XIV,  figs.  0.  6a.] 

Figures  1-6.  Interiors  of  ventral  valves  illustrating  variations  in  size,  form,  and  position  of  the  central,  middle  lateral, 
and  outside  lateral  muscle  scars.  From  Locality  9d,  Upper  Cambrian  Obolus  sandstone,  at  Jaggowal, 
east  of  Reval,  Esthonia,  Russia.     U.  S.  Nat.  Mus.  Cat.  No?.  .!jl.524a-f,  respectively. 

7  and  8.  Interiors  of  ventral  valves  from  Locality  395b,  Upper  Cambrian  Obolus  sandstone,  at  Ilgast,  Esthonia, 
Russia,  showing  variation  in  form  and  arrangement  of  the  muscle  scars,  central  depression,  etc.  V.  S. 
Nat.  Mus.  Cat.  Nos.  51525a  and  51525b,  respectively. 

10,  11,  and  12.  Interiors  of  ventral  valves  from  Locality  9d,  Upper  Cambrian  Obolus  sandstone,  at  Jaggowal, 
Esthonia,  Russia,  showing  variation  in  the  form  and  arrangement  of  the  muscle  scars,  central  depres- 
sion, etc.  U.  S.  Nat.  Mus.  Cat.  Nos.  35238a,  35238b,  and  3523Sc,  respectively.  Specimens  figured 
by  Walcott  [1898b,  PL  XXVI,  figs.  3-5,  respectively]. 

13.  Fragment  of  the  interior  of  a  ventral  valve  from  Locality  9d,  Upper  Cambrian  Obolus  sandstone,  at  Jaggo- 

wal, Esthonia,  Russia,  in  which  the  heart-shaped  cavity  is  nearly  lost,  and  in  which  the  centrals, 
middle  laterals,  and  outside  laterals  are  crowded  into  a  narrow  space.  The  drawing  of  the  central 
and  outside  lateral  scars  is  somewhat  conventionalized.  U.  S.  Nat.  Mus.  Cat.  No.  35238d.  Specimen 
figured  by  Walcott  [1898b,  PL  XXVI,  fig.  6]. 

14,  15,  16,  and  17.  Interiors  and  posterior  portions  of  dorsal  valves  from  Locality  395b,  L^pper  Cambrian 

Obolus  sandstone,  at  Ilgast,  Esthonia,  Russia,  showing  the  variation  in  position  of  muscle  scars. 
U.  S.  Nat.  Mus.  Cat.  Nos.  51525c-f,  respectively. 

Obolus  apollinis  maximus  ilickwitz  (p.  384). 

[PI.  XIV.  figs.  7  and  7a.] 


Figure  9.  Interior  of  a  ventral  valve  in  which  the  thickening  of  the  shell  is  very  great. 
Cambrian  Obolus  sandstone,  at  Joa,  near  Jegelecht,   Esthonia,  Russia. 
51528a. 
28 


From  Locality  395,  Upper 
U.  S.  Nat.  Mus.  Cat.  No. 


U    S.   GEOLOGICAL  SURVEY 


MONOGRAPH   LI     PL.  VII 


FRANCES  W1E9ER  DEL. 


ELiOTifPE    CO    BOSTON 


PLATE   VIII. 


29 


PLATE  VIII. 

a.  Central  lateral  space  of  area.  o'.  Overlapping  of  lines  of  growth  of  area. 

a'.  Outer  lateral  space  of  area.  p.  Pedicle  groove. 

c.  Trapezoidal  area,  including  central,  middle  pvs.  Peripheral  branches  of  the  vascular  system. 

lateral,  and  outside  lateral  muscle  scars.  ps.  Parietal  band.' 

f.  Flexure  line  of  area.  s.  Median  septum, 

h.  Central  mtiscie  scar.  v.  Visceral  cavity, 

i.  Transmedian  muscle  scar.  vs.  Main  vascular  sinus, 

j.  Anterior  lateral  muscle  scar.  ivs.  Lateral  branches  of  vascular  system. 

k.  Middle  lateral  muscle  scar.  x.  Heart-shaped  cavity. 
1.  Outside  lateral  muscle  scar. 

Obolus  matixalis  (Hull)  (p.  400). 

Figure  1.  E.icterior  of  an  almost  perfect  ventral  valve  from  Locality  328e,  a  Middle  Cambrian  horizon  in  the  "St.  Croix 
sandstone,"  St.  Croix  Falls,  Wisconsin.     U.  S.  Nat.  Mus.  Cat.  No.  51.564a. 

la.  Large,  partly  exfoliated  ventral  valve  from  Locality  67c,  Upper  C'ambrian  sandstone,  Tatur  Hill,  Burnet 
County,  Texas,  showing  the  radial  striation  of  the  inner  layers  of  the  .shell.  U.  S.  Nat.  Mus.  Cat.  No. 
52420a. 

lb.  Partly  exfoliated  ventral  valve  from  Locality  67,  L'pper  Cambrian  sand.stone,  Tatur  Hill,  Burnet  County, 
Texas.     U.  S.  Nat.  Mus.  Cat.  No.  52419a. 

Ic.  Partly  exfoliated  ventral  valve  associated  with  the  specimen  represented  by  figure  1.  U.  S.  Nat.  Mus. 
Cat.  No.  51.564b. 

Id.  Cast  of  the  interior  of  a  ventral  valve  showing  the  details  of  the  interior  of  the  shell  with  unusual  clear- 
ness, from  Locality  82b,  Upper  Cambrian  "St.  Croix  sandstone,"  Taylors  Falls,  Chisago  County, 
Minnesota.     U.  S.  Nat.  Mus.  Cat.  No.  51563a. 

le.  Cast  of  the  interior  of  a  ventral  valve  associated  with  the  valve  represented  by  figure  1.  U.  S.  Nat.  Mus. 
Cat.  No.  51564c. 

If.  Interior  of  a  broken  ventral  valve  from  Locality  339d,  Upper  Cambrian  "St.  Croix  sandstone"  at  Taylors 
Falls,  Minnesota,  showing  the  thickened  shell  under  the  visceral  area.  U.  S.  Nat.  Mus.  Cat.  No. 
51563c. 

Ig.  Interior  of  a  ventral  valve,  in  which  there  is  no  special  thickening  beneath  the  visceral  area,  associated 
with  the  specimen  represented  by  figure  If.     U.  S.  Nat.  Mus.  Cat.  No.  51563d. 

Ih.  Cast  of  the  interior  of  a  dorsal  valve  associated  with  the  specimen  represented  by  figure  Id.  U.  S.  Nat. 
Mus.  Cat.  No.  51563b. 

li.  Cast  of  the  interior  of  a  dorsal  valve  associated  with  the  valve  represented  by  figures  1,  Ic,  and  le.  L".  S. 
Nat.  Mus.  Cat.  No.  51564d. 

Ij.  Interior  of  a  ventral  valve  in  which  there  has  been  a  considerable  thickening  of  the  shell  .«o  as  to  form  a 
platform  to  which  the  muscles  and  visceral  parts  were  attached.  From  Localit\  339d,  I'pper  Cam- 
brian "St.  Croix  sandstone."  Taylors  Falls,  Minnesota.     \J.  S.  Nat.  Mus.  Cat.  No.  51.563c. 

Ik.  Partly  exfoliated  dorsal  valve  from  Locality  71,  I'pper  Cambripn  limestone.  Cold  Creek  Canyon,  Burnet 
County,  Texas.     U.  S.  Nat.  Mus.  Cat.  No.  51566a. 

Obolus  tetonensis  ninus  Walcott  (p.  4LS). 

[PI.  XI,  figs.  1,  la-g.] 

Figure  1  1.  Ventral  vSlve,  showing  the  strongly  marked  radiating  stria;  of  the  inner  layers, 
lin.  Cast  of  the  interior  of  a  ventral  valve. 
In.  Cast  of  the  interior  of  a  dor.sal  valve, 
lo.  Cast  of  the  interior  of  a  partly  exfoliated  dorsal  valve. 

The  specimens  represented  by  figures  1 1  to  lo  are  from  Locality  68,  Upper  Cambrian  saiidstone,  Packsaddlc  Moun- 
'  tain,  Llano  County,  Texas.     U.  S.  Nat.  Mus.  Cat.  Nos.  51644a-d,  respectively. 

Obolus  namouna  Walcott  (p.  406). 

Figure  2.  Cast  of  the  interior  of  a  ventral  valve,  the  type  specimen,  associated  on  the  same  hand  spe<-imen  with 
the  shells  of  Obolus  rliai  represented  by  figiu-es  la  and  lb,  Plate  IX,  from  Locality  98,  Upper  Cambrian 
"St.  Croix  sandstone,"  Eau  Claire,  Wisconsin.     U.  S.  Nat.  Mus.  Cat.  No.  27304a. 
30 


U.   S.   GEOLOGICAL  SURVEY 


MONOGRAPH   LI      PL.   VIII 


FRANCES  WIESER  DEL. 


LlOT/PC   CO    90SI0N 


PLATE  VIII.  31 

Obolus  NAMOtJNA  Walcott— Continued. 

Figure  2a.  Cast  of  the  interior  of  a  dorsal  valve  associated  on  the  same  hand  specimen  with  the  specimen  represented 
by  fagure  2.  The  remarkable  feature  of  this  specimen  is  the  continuation  of  the  lines  of  growth  of  the 
area  far  forward  on  the  shell.     U.  S.  Nat.  Mus.  Cat.  No.  27304b. 

Obolus  matinalis  (Hall)  ?  WaU-ott  (p.  402). 

Figures  3  and  3a.  Ventral  and  dorsal  valves  of  partly  e.xfoliated  shells  from  Locality  C54,  Upper  Cambrian  Chau- 
mitien  limestone  two-thirds  mile  west  of  Tsinan,  Shantung,  China.  U.  S.  Nat.  Mus.  Cat.  Nos 
52o33a  and  o2r)33b,  respectively. 


PLATE    IX. 


62667°— VOL  51,  pt  2—12 ^3  33 


PLATE  IX. 


Central  lateral  space  of  area. 

Outer  lateral  sjiace  of  area. 

Trapezoidal  area,  includinf;  central,  middle 

lateral,  and  outside  lateral  muscle  scars. 
Flexure  line  of  area. 
Central  muscle  scar. 


j.  .\nterior  lateral  muscle  scar. 

p.  Pedicle  groove, 
ps.  Parietal  band. 

V.  Visceral  cavity, 
vs.  Main  vascular  sinus. 

X.  Heart-shaped  cavity. 


Oboli^s  RHEA  Walcott  (p.  410). 

Figure  1.  Cast  of  the  interior  of  a  ventral  valve,  the  type  specimen,  from  Locality  98,  T'])per  Cambrian  "St.  Croix 
sandstone,"  Eaii  Claire,  Wisconsin,  which  shows  the  median,  pestlo-shaped  ridge  that  filled  the 
corresponding  groove  on  the  interior  of  the  shell,  (.'asts  of  the  lines  of  growth  and  the  visceral  area 
are  also  finely  preserved.     U.  S.  Nat.  Mus.  Cat.  No.  27300a. 

la.  Cast  of  the  interior  of  a  ventral  valve  from  Locality  98,  Upper  Cambrian  "St.  Croix  sandstone,"  Eau 
Claire,  Wisconsin,  in  which  some  of  the  details  of  the  anterior  part  of  the  visceral  cavity  are  more 
clearly  defined  than  in  the  specimen  represented  by  figure  1.     XJ.  S.  Nat.  Mus.  Cat.  No.  27300b. 

lb.  A  dorsal  valve,  associated  on  the  same  hand  specimen  with  the  specimen  represented  by  figure  la,  from 
which  the  shell  has  been  almost  wholly  exfoliated.     U.  S.  Nat.  Mus.  Cat.  No.  27300c. 

The  specimens  represented  in  figures  la  and  lb  are  on  the  same  slab  of  sandstone  as  the  two  specimens  of  Obolus 
namouna  represented  by  figures  2  and  2a,  Plate  VIII. 

Figure  Ic.  Cast  of  the  interior  of  a  dorsal  valve  from  Locality  84,  a  Middle  Cambrian  horizon  in  the  "St.  Croix  sand- 
stone," Dresbach,  Minnesota,  showing  the  area  and  traces  of  the  vascular  markings.     U.  S.  Nat. 
■  Mus.  Cat.  No.  52430a. 

Obolus  eefulgens  Matthew  (p.  409). 

Figure  2.  Cast  of  the  interior  of  a  ventral  valve,  the  type  specimen,  that  is  flattened  in  the  shale.  University  of 
Toronto,  Canada.  Redrawn  from  the  specimen  figured  by  Matthew  [1892,  PI.  XII,  fig.  6d  (ventral)] 
as  Obolus  rrfiiUjens:  and  copied  by  him  [1903,  PI.  XI,  fig.  4a]  as  MonoboUna  rcfidgens. 

2a.  Cast  of  the  interitjr  of  a  dorsal  valve  that  preser\-cs  the  original  convexity.  L^niversitj'  of  Toronto,  Canada. 
Redrawn  from  the  specimen  figured  by  Matthew  [1892,  PI.  XII,  fig.  6d  (dorsal)]  as  Obolus  refidgens; 
and  copied  by  him  [1903,  PI.  XI,  fig.  4b]  as  MonoboUna  refidgens. 

2b.  Ventral  valve  flattened  in  the  shale  and  compressed  laterally  so  as  to  give  it  more  the  outline  of  Lingulella 
than  of  Obolus.     L^niversity  of  Toronto,  Canada. 

2c  and  2d.  Dorsal  valves  flattened  in  the  shale  and  slightly  distorted.     L'nivcrsity  of  Toronto,  Canada. 

The  specimens  represented  all  occur  in  Locality  308,  LTpper  Cambrian,  Division  3c  of  Matthew,  Navy  Island, 
St.  John  Harbor,  New  Brunswick.  Specimens  represented  by  figures  2  and  2a  occur  in  an  arenaceous  shale  which 
preserves  the  specimens  in  better  condition  than  in  the  argillaceous  shales. 

Oboli's  pandemia  Walcott  (p.  407). 

P^GURE  3.  Exterior  of  a  slightly  flattened  and  distorted  ventral  valve.     U.  S.  Nat.  Mus.  Cat.  No.  27301a. 

3a.  Cast  of  the  interior  of  a  ventral  valve,  the  type  specimen,  that  has  been  compressed  in  its  posterior  portion 

so  as  to  force  the  visceral  ca\'ity  back  nearly  to  the  area.     U.  S.  Nat.  Mus.  Cat.  No.  27301b. 
3b.  Interior  of  the  ventral  valve  showing  an  elevated  pestle-shaped  median  ridge  that  occupies  the  place  of 

the  heart-shaped  cavity  of  most  species  of  Obolus.  V.  S.  Nat.  Mus.  Cat.  No.  27301c. 
3c.  Cast  of  the  interior  of  a  dorsal  valve,  showing  the  area.  U.  S.  Nat.  Mus.  Cat.  No.  27301d. 
3d.  Cast  showing  part  of  (he  interior  of  a  dorsal  valve,  showing  traces  of  the  central  muscle  sqars,  and  the 

thick  lamination  of  the  .shell  toward  the  margin.     U.  S.  Nat.  Mus.  Cat.  No.  27301e. 

The  specimens  represented  are  all  from  Locality  10a,  Middle  Cambrian,  Bays  Mountains,  Knoxville,  Tennessee. 

Obolus  lopeki  Walcott  (p.  395). 

FiGUKE  4.  Imperfect  ventral  valve  from  Locality  335a,  Cambro-Ordovician  sandstone,  Cement  Creek,  3  miles  north 
of  Hot  Springs,  Ouray  County,  Colorado,  showing  the  general  form  and  the  several  layers  forming 
the  shell.     U.  S.  Nat.  Mus.  Cat.  No.  27303a. 
4a.  Partly  exfoliated  dorsal  valve,  the  type  specimen,  associated  with  the  specimen  represented  ly  figure  4. 
V.  S.  Nat.  Mus.  Cat.  No.  27303b. 
34 


U.  S.   GEOLOGICAL  SURVEY 


MONOGRAPH  L'     iL.  I/, 


PLATE  IX.  35 

Obolus  tetonensis  Walcott  (p.  417). 

Figure  5.  A  ventral  valve,  the  type  specimen,  with  the  anterior  portion  of  the  shell  exfoliated,  from  Locality  4e, 

Middle  Cambrian  limestone,  Teton  Mountains,  Wyoming.  U.  S.  Nat.  Mus.  Cat.  No.  51639a. 
5a.  Dorsal  valve  associated  with  specimen  represented  by  figure  5.  U.  S.  Nat.  Mus.  Cat.  No.  51G39b. 
5b.  Outline  of  the  two  valves,  showing  their  convexity.     Drawn  from  specimen  associated  with  specimens 

represented  by  figures  5  and  5a.     U.  S.  Nat.  Mus.  Cat.  No.  51639c. 
5c.  A  small  ventral  \alve  from  Locality  4m,  Middle  Cambrian  sandstone  in  the  Teton  Mountains,  Wyoming. 

r.  S.  Nat.  Mus.  Cat.  No.  35220a. 
5d.  Dorsal  valve  associated  with  specimen  represented  by  figure  5c.     This  shell  may  belong  to  some  other 

species.     U.  S.  Nat.  Mus.  Cat.  No.  35220b. 

Obolus  woetheni  Walcott  (p.  421). 

[Te.xt  flgs.  39A-D,  p.  421.] 

Figure  5e.  A  very  finely  preserved  interior  of  a  small  dorsal  valve,  the  type  specimen,  from  Locality  54u,  Middle 
Cambrian  limestone,  2  miles  southeast  of  Malade,  Idaho.  U.  S.  Nat.  Mus.  Cat.  No.  51638a.  Copied 
from  Walcott  [1908d,  PI.  VII,  fig.  17]. 


PLATE   X. 


37 


PLATE  X. 

c.  Trapezoidal  area,  including  central,  middle  s.  Median  septum. 

lateral,  and  outside  lateral  muscle  scars.  v.  V'isceral  cavity, 

h.  Central  muscle  scar.  vs.  Main  vascular  sinus. 
j.  Anterior  lateral  muscle  scar.  x.  Ilcart-shaped  cavity. 

Obolus  mickwitzi  Walcott  (p.  403). 

Figure  1.  Cast  of  a  small  veutral  valve,  the  type  specimen,  showing  tho  dfejily  impressed  vascular  and  vi.sceral  mark- 
ings.    It  will  be  noted  that  the  visceral  cavity  extends  far  forward.     U.  S.  Nat.  Mas.  Cat.  No.  27299a. 

la.  Cast  of  the  interior  of  a  ventral  valve  in  which  the  visceral  cavity  is  much  larger  proportionally  than  that 
represented  in  figure  1,  and  in  which  the  areas  occupied  by  the  central,  middle  lateral,  and  outside 
lateral  scars  are  unusually  large  and  i)rominent.  More  than  two-thirds  of  the  entire  length  of  the 
shell  is  taken  up  by  the  visceral  area.     U.  S.  Nat.  Mus.  Cat.  No.  27299b. 

lb.  Portion  of  the  cast  of  a  small  ventral  valve  in  which  the  interior  markings  have  been  still  more  deejdy 
impressed  than  in  the  specimens  shown  by  figures  1  and  la.  The  heart-shaped  cavity  (x),  the  trape- 
zoidal area  (c),  and  the  main  vascular  sinus  (vs)  must  have  been  placed  upon  a  strongly  built  up 
platform  in  the  interior  of  the  shell.     U.  S.  Nat.  Mus.  Cat.  No.  27299c. 

Ic.  Cast  of  the  interior  of  a  large  ventral  valve  in  which  the  visceral  area  is  limited  to  the  ])osterior  half  of  the 
shell.     U.  S.  Nat.  Mus.  Cat.  No.  27299d. 

Id.  Cast  of  the  interior  of  a  large  dorsal  valve  which  shows  the  relative  position  of  the  central  (h)  and  anterior 
lateral  (j)  muscle  scars,  and  the  form  of  the  visceral  cavity.     U.  S.  Nat.  Mus.  Cat.  No.  27299e. 

le.  Partly  exfoliated  dorsal  valve  which  illustrates  the  lamcllated  character  of  the  shell  and  the  strong 
concentric  undulations  of  growth  which  appear  on  some  specimens.  V.  S.  Nat.  Mu.'i.  Cat.  No. 
27299f. 

If.  Cast  of  a  large  dorsal  valve  in  which  the  visceral  area  is  mainly  upon  the  posterior  half,  as  in  the  ventral 
valve  represented  by  figure  Ic.     l\  S.  Nat.  Mus.  Cat.  No.  27299g. 

Ig.  Cast  of  the  interior  of  a  small  dorsal  valve  in  which  the  visceral  area  occupies  the  central  iiortion  of  the 
shell.     U.  S.  Nat.  Mus.  Cat.  No.  27299h. 

Ih.  Cast  of  the  interior  of  a  dorsal  valve  showing  a  remarkable  development  of  the  area  about  the  central 
muscle  scars.    U.  S.  Nat.  Mus.  Cat.  No.  272991. 

li.  Cast  of  the  interior  of  a  ventral  valve  in  which  the  main  vascular  sinus  and  other  inlerior  markings  of 
the  shell  are  less  deeply  impressed  than  in  specimens  represented  by  figures  la  and  11>, 

The  specimens  represented  in  figures  1,  la-i  are  from  Locality  79,  Upper  Cambrian  sandstone,  at  Hudson,  Wis- 
consin. 

Figure  Ij.  Cast  of  a  ventral  valve  which  is  somewhat  doubtfully  referred  to  this  species,  owing  to  its  not  showing  the 
same  strong  interior  markings.  This,  however,  may  be  the  result  'of  the  condition  of  ]ir('servation. 
U.  S.  Nat.  Mus.  Cat.  No.  56937a. 
Ik.  Partly  exfoliated  dorsal  valve  associated  with  the  specimen  represented  by  figure  Ij.  It  is  probable 
that  a  larger  collection  of  material  would  show  that  figures  Ij  and  Ik  represent  a  distinct  species. 
IT.  S.  Nat.  Mus.  Cat.  No.  56937b. 

The  specimens  represented  in  figures  Ij  and  Ik  are  from  Locality  79b,  UpiJcr  Cambrian  .sandstone  at  Hudson, 
Wisconsin,  a  slightly  diSerent  horizon  than  the  one  containing  the  specimens  represented  in  figures  1,  la-i. 

Obolus  u^ra  (Hall  and  Wliitfield)   (p.  399). 

FiouKE  2.  Partly   exfoliated   and    broken   ventral   valve   from   Locality  313j,   Upper  Cambrian  limestone.  Eureka 

district,  Nevada.     U.  S.  Nat.  Mus.  Cat.  No.  24552a. 
2a.  Partly  exfoliated  dorsal  valve  associated  with  the  specimen  represented  by  figure  2.     U.  S.  Nat.  Mus. 

Cat.  No.  24552b.     Type  specimen  figured  by  Hall  and  WTiitfiekl  [1877,  PI.  I,  fig.  6]  as  Lingulepis  msera. 
2b.  More  elongated,  partly  exfoliated  dorsal  valve  from  Locality  313j,  Upper  Cambrian  limestone,  Eureka 

district,    Nevada.     U.  S.  Nat.  Mus.  Cat.   No.  24552c.     Specimen  figured  by  Hall  and  Whitfield 

[1877,  PI.  I,  fig.  5]  as  Lingulepis  inxra. 
2c.  Crushed  and  partly  exfoliated   ventral   valve,  doubtfully  referred   to  this  species,  from   Locality  205, 

limestone  forming  passage  beds  between  the  Upper  Cambrian  and  the  Ordovician,  on  Roundtop 

Mountain,  Eureka  district,  Nevada.     U.  S.  Nat.  Mus.  Cat.  No.  51562a. 
38 


U.  S.   GEOLOGICAL  SURVEY 


MONOGRAPH   LI     PL.  X 


FRANCES  WIESER  DEL. 


PLATE  X.  39 

Obolus  m^ra  (Hall  juul  Wliitlield) — Continued. 

Figure  2d.  Exfoliated  ventral  valve  from  Locality  61,  I'pper  Cambrian  Dunderberg  shale,  south  of  the  Hainburg 

mine,  Eureka  district,  Nevada,  showing  outline  of  visceral  area.     U.  S.  Nat.  Mus.  Cat.  No.  515Gla. 

2e.  Partly  exfoliated  ventral  valve,  showing  radial  striation  of  interior  layers  of   the  shell.  Locality  88, 

Middle  Cambrian  Secret  Canyon  shale,  New  York  and  Secret  canyons,  Eureka  district,  Nevada. 

U.  S.  Nat.  Mus.  Cat.  No.  olofiOa. 

Oboi.vs  anceps  Walcott   (p.  380). 

Figure  3.  Partly  exfoliated  ventral  valve.     U.  S.  Nat.  Mus.  Cal.  No.  27302a. 

3a.  Partly  exfoliated  ventral  valve  showing  the  area.     L'.  S.  Nat.  Mus.  Cat.  No.  27302b. 

3b.  Cast  of  the  interior  of  a  dorsal  valve,  the  type  specimen,  showing  the  area  and  traces  of  the  vascular 

markings.     I".  S.  Nat.  Mus.  Cat.  No.  27302c. 
3c.  More  elongated  dorsal  val\-e  than  that  represented  by  figure  3b.     U.  S.  Nal.  Mu.s.  Cat.  No.  27302d. 

The  specimens  represented  in  figures  3,  3a-c  are  all  from  Locality  63.  Lower  Ordovician  Pogonip  limestone,  north- 
east of  Adams  Hill,  Eureka  district,  Nevada. 

Figure  3d.  Ventral  valve.     U.  S.  Nat.  Mus.  Cat.  No.  .51541a. 

3e.  Partly  exfoliated  dorsal  valve  showing  interior  layers  of  the  shell.     U.  S.  Nat.  Mus.  Cat.  No.  51541b. 
3f.  Exterior  of  dorsal  valve.     U.  S.  Nat.  Mus.  Cat.  No.  51541c. 

The  specimens  represented  in  figures  3d-f  are  from  Locality  61,  Upper  Cambrian  Dunderberg  shale,  south  of  the 
Hamburg  mine,  Eureka  district,  Nevada. 

Obolus  .sp.  uiidt.  a  Walcott  (p.  422). 

Figure  4.  Ventral  valve  compressed  in  shaly  limestone  of  Locality  338v,  I^ower  Ordovician,   1  mile  southwest  of 
Middle  Granville,  Washington  County.  New  York.     U.  S.  Nat.  Mus.  Cat,  No.  51G52a 


PLATE   XI. 


41 


PLATE  XI. 

a.  Area.  h.  Central  muscle  scar, 

c.  Trapezoidal  area,  including  central,  middle  j.  Anterior  lateral  muscle  scar, 

lateral,  and  outside  lateral  muscle  scars. 

Obolus  tetonensis  ninus  Walcott  (p.  418). 

[PI.  VIII,  figs.  11-0. J 

Figures  1  and  1'.  Top  and  side  views  of  exterior  of  ventral  valve,  the  type  specimen.     V.  S.  Xal.  Mils'.  Cat. 

No.  51(i4;!a. 
la.  Partly  exfoliated  ventral  valve.     V.  S.  Nat.  Mus.  Cat.  No.  51643b. 

lb.  Interior  of  ventral  valve,  show-ing  outline  of  visceral  area.     U.  S.  Nat.  Mils.  Cat.  No.  51643c. 
Ic.  Dorsal  vah'e,  showing  lamellation  of  shell.     U.  S.  Nat.  Mus.  Cat.  No.  51643d. 
Id  and  Id'.  Exfoliated  dorsal  valve,  showing  striation  (jf  interior  layers  of  shell.     1'.  K.  Nat.  Mus.  Cat.  No. 

51643e. 
le  and  If.  Exfoliated  dorsal  valves,  showing  character  of  interior  layers  of  shell  and  variation  in  form  from 

specimens  represented  by  figures  Ic  and  Id.    U.  S.  Nat.  Mus.  Cat.  Nos.  51643f  and  51643g,  respectively. 
Ig.  Cast  of  broken  dorsal  valve,  showing  anterior  position  of  visceral  area,  and  the  central  and  anterior  lateral 

scars.     U .  S.  Nat.  Mus.  Cat.  No.  51643h. 

The  specimens  represented  are  all  from  Locality  9r,  Upper  Cambrian  limestone  in  the  Reagan  sandstone,  Coman- 
che County,  Oklahoma. 

Obolus  (Westonia)  themis  Walcott  (p.  466). 

Figure  2.  Exterior  of  ventral  valve,  the  type  specimen,  showing  broken  edges  of  lamellae  of  the  shell.     U.  S.  Nat. 

Mus.  Cat.  No.  51732a. 
2a.  Dor-sal  valve,  showing  the  .same  shell  characters  as  figure  2.     U.  S.  Nat.  Mus.  Cat.  No.  51732b. 
2b.  Broken  ventral  valve,  showing  cast  of  the  visceral  cavity  and  main  vascular  trunks.     U.  S.  Nat.  Mus. 

Cat.  No.  51732c. 
2c.  Partly  exfoliated  dorsal  valve,  posterior  margin  broken  away.     I'.  S.  Nat.  Mus.  Cat.  No.  51732d. 

The  specimens  represented  are  all  from  Locality  17c,  Middle  Cambrian  sandy  limestone  on  Grand  \'iew  trail, 
south  side  Grand  Canyon  of  the  Colorado,  Arizona. 

Obolus  ismene  Walcott  (p.  393). 

Figure  3.  Portion  of  .-entral  valve,  the  type  specimen,  showing  cardinal  slopes  and  the  striation  of  one  ^^f  the  inner 
layers  of  shell.     U.  S.  Nat.  Mus.  Cat.  No.  51545a. 
3a.  Partly  exfoliated  dorsal  valve.     V .  S.  Nat.  Mus.  Cat.  No.  51545b. 
3b.  Interior  of  a  dorsal  valve  showing  area.    L".  S.  Nat.  Mus.  Cat.  No.  51545c. 

The  specimens  represented  are  all  from  Locality  369,  Upper  Cambrian  sandstone  in  the  Elvins  formation,  Flat 
River,  St.  Francois  County,  Missouri. 

Obolus  nundina  Walcott  (p.  406). 

Figure  4.  Ventral  valve,  the  type  specimen,  showing  the  characteristic  strong  concentric  ridges. 
4a.  Partly  exfoliated  dorsal  valve. 

The  specimens  represented  are  on  the  same  piece  of  limestone  from  Locality  14b.  Upper  Cambrian,  Cold  Creek, 
Llano  County,  Texas.     U.  S.  Nat.  Mus.  Cat.  Nos.  51587a  and  51.587b,  respectively. 

Obolus  acadicus  Walcott  (p.  380). 

Figure  5.  Cast  of  the  interior  of  a  dorsal  valve,  the  type  specimen,  from  Locality  3h.  I'pper  Cambrian  shale,  McNeil 
Brook,  Cape  Breton,  Nova  Scotia.  U.  S.  Nat.  Mus.  Cat.  No.  51540a.  The  i)i)sterior  portion  of  the 
shell  was  restored  from  another  specimen  (Catalogue  No.  5I.540b),  the  two  being  counterparts. 

Obollts  pheres  Walcott  (p.  408). 

Figures  6  and  fia.  Views  of  partly  exfoliated  ventral  valves,  showing  thickness  of  the  lamellated  .^hell.     U.  S.  Nat. 
Mus.  Cat .  No.  51.589a  and  51.589b,  respectively.     Figure  6  represents  the  type  specimen. 
Gb.  Imperfect  dorsal  valve.     U.  S.  Nat.  Mus.  Cat.  No.  51589c. 

The  specimens  represented  are  all  from  Locality  lOv,  U|>per  Candirian  shale  near  Baraboo,  Wi.-sconsin. 

42 


U.  S.   GEOLOGICAL  SURVEY 


MONOGRAPH   LI     PL.  X! 


FRANCES  WItSEB  DEL, 


HELiorvpE  CO  ao5TON, 


PLATE  XI.  43 

Obolus  shansiensis  Walcott  (p.  415). 

Figure  7.  Broad  form  of  the  ventral  valve  from  Locality  C32,  Middle  Cambrian  river  drift  on  the  Nankiang,  1  mile 

south  of  Chonpinghien,  Shensi,  China.    U.  S.  Nat.  Mus.  Cat.  No.  52537a. 
7a.  Narrow  form  of  the  ventral  valve,  the  type  specimen,  from  Locality  C37,  Middle  Cambrian  Kichou 

limestone,  8  miles  south  of  Tinghianghien,  Shansi,  China.     U.  S.  Nat.  Mus.  Cat.  No.  52538a. 
7b.  Broad  form  of  the  dorsal  valve  associated  with  the  ventral  valve  represented  by  figure  7.     U.  S.  Nat.  Mus. 

Cat.  No.  52537b. 
7c.  Narrow  form  of  the  dorsal  valve  associated  with  the  ventral  \-alve  represented  by  figure  7a.     V.  S.  Nat. 

Mus.  Cat.  No.  52538b. 

Obolus  minimus  Walcott  (p.  404). 

Figure  8.  A  partly  exfoliated  ventral  valve,  the  type  specimen,  showing  the  cast  of  the  visceral  area  and  the  main 
vascular  canals. 
8a.  Exterior  of  dorsal  valve. 

The  specimens  represented  are  both  from  Locality  CI,  Middle  Cambrian  Kiuluiig  limestone,  2  miles  south  of  Yen- 
chuang,  Sintai  district,  Shantung,  China.     U.  S.  Nat.  Mus.  Cat.  Nos.  52534a  aud  52534b,  respectively. 

Obolus  obscurus  Walcott  (p.  406). 

Figure -Q.  Interior  of  an  imperfectly  preserved  dorsal  valve,  the  type  specimen.     U.  S.  Nat.  Mus.  Cat.  No.  52536a. 
9a.  Exterior  of  an  exfoliated,  partly  restored  dorsal  valve.     U.  S.  Nat.  Miis.  Cat.  No.  52536b. 

The  specimens  represented  in  figures  9  and  9a  are  both  from  Locality  C63,  Middle  Cambrian  sandy  shale  at  the 
base  of  the  Kiulung  group,  3.5  miles  southwest  of  Yenchuang,  Sintai  district,  Shanlung,  China. 

Figure  9b.  Partly  exfoliated  and  broken  ventral  valve,  showang  concentric  and  radiating  lines  on  the  inner  layers 
of  the  shell.     U.  S.  Nat.  Mus.  Cat.  No.  52535a. 
9c.  Enlargement  of  the  concentric  striae  of  the  exterior  surface.     U.  S.  Nat.  Mus.  Cat.  No.  52535b. 
9d.  Exterior  surface  of  a  broken  dorsal  valve.    U.  S.  Nat.  Mus.  Cat.  No.  52535c. 

The  specimens  represented  in  figures  9b-d  are  from  Locality  C75,  Middle  Cambrian  limestone  near  the  base  of  the 
Kichou  formation,  4.5  miles  south  of  Wutaihien,  Shansi,  China. 


PLATE   XII. 


45 


PLATE  XII. 

a.  Trapezoidiil  area,  iiicluditifj  centra!,  middle  j.  Anterior  lateral  muscle  scar. 

lateral,  and  outside  lateral  muscle  scars.  p.  Pedicle  groove, 

h.  Central  muscle  scar.  vs.  Main  vascular  sinus, 

i.  Transmedian  nuisde  scar.  jvs.  Lateral  branches  of  the  vascular  system. 

Obolus  feistmanteli  (Barrandp)  (p.  391). 

[PI.  XII,  figs.  9  and  93.) 

Fir.uKE  1.  Interior  of  ventral  valve.     Copied  from  Barrande  [1879b,  PI.  CVI,  fii^.  iv:  7A]. 

la.  Cast  of  exterior  surface  of  ventral  valve,  showing  traces  of  concentric  strise  and  lines  of  growth.  Copied 
from  Barrande  [1879b,  PI.  CVI,  fig.  iv:  llA]. 

lb.  Cast  of  interior  of  ventral  valve.  Original  in  the  collection  of  the  Museum  of  Comparative  Zoology,  Cam- 
bridge, Massachusetts;  cast  in  the  United  States  National  Museum  (Cat.  No.  57088a). 

Ic.  Cast  of  interior  of  ventral  valve,  showing  lateral  vascular  canals.  Original  in  the  Museum  of  Com- 
parative Zoology;  cast  in  the  United  States  National  Museum  (Cat.  No.  .57088b). 

Id.  Interior  of  the  type  specimen,  a  ventral  valve.     Copied  from  Barrande  [lS79b,  PI.  CVI,  fig.  iv:  4 A]. 

le.  Cast  of  the  interior  of  a  dorsal  valve,  showing  traces  of  lateral  va.scular  canals.  Original  in  the  Museum  of 
Comparative  Zoology;  cast  in  the  United  States  National  Museum  (Cat.  No.  .570S8c).     (See  fig.  9a.) 

If.  Enlargement  of  a  portion  of  a  partly  exfoliated  shell,  showing  structure  of  shell.  Copied  from  Barrande 
[1879b,  PI.  CVI,  fig.  IV :  12f]. 

The  specimens  represented  are  all  from  Locality  3031,  Lower  Ordovician  sandstone,  Etage  dl,  Kruschna  nora, 
Bohemia. 

Obolits  ?  ANCiLLUS  (BaiTaiide)  (p.  381). 

Figure  2.  Partly  exfoliated  ventral  valve,   the  type  specimen,  from  Locality  303g,  Lower  Ordovician,  Etage  dl, 
Rabenberg,  Bohemia.     Copied  from  Barrande  [1879b, -PI.  CXI,  fig.  vi:  3A]. 

Obolus  complexus  Barramle  (p.  387). 

|P1.  XII,  figs.  Sand  8a.] 

FiGVRE  3.  Cast  of  interior  of  ventral  valve,  the  type  specimen,  from  Locality  3031,  Lower  Ordovician,  Etage  dl, 
Kruschna  Hora,  Bohemia.     Copied  from  Barrande  [1879b,  PI.  CLII,  fig.  ii:  4A]. 
3a.  Interior  of  dorsal  valve  from  Locality  3031,  Lower  Ordovician,  Etage  dl,  Kruschna  Hora,  Bohemia.    Copied 
from  Barrande  [lS79b,  PI.  CXIII,  fi-.  v:  A]. 

Obolus?  mirandus  (Barrande)  (p.  405). 

Figure  4.  Ventral  valve,  the  type  specimen,  from  Locality  303k,  Lower  Ordovician,  Etage  dl,  Hradischt,  Bohemia. 
Copied  from  Barrande  [1879b,  PI.  CXI,  fig.  i:  3A]. 
4a.  Dorsal?  valve  from  Locality  303k,    Lower  Ordo\-ician,   Etage  dl,   Hradischt,   Bohemia.     Copied  from 
Barrande  [1879b,  PI.  CXI,  fig.  i:  lA]. 

Obolus?  advenus  Barrande  (p.  380). 

Figure  5.  Cast  of  interior  of  ventral  valve,  the   type  specimen,  from  Locality  303d,   Lower  Ordovician,  Etage  dl, 
Swarow,  Bohemia.    Copied  from  Barrande  [1879b,  PI.  XCV,  fig.  iv:  2A]. 
oa  and  .'ilj.  Exterior  and  side  ^'iew  of  dorsal?  valve  from  Locality  303d,  Lower  Ordovician,  Etage  dl,  Swarow, 
liohemia.     Co))iod  from  Barrande  [lS7llb,  PI.  XCV,  figs,  iv:  lA  and  2B,  respectively]. 

Odolus?  rokitzanensis  Barnuide  (p.  411). 

FiGURK  G.  Cast  of  the  interior  of  a  ventral  valve,  the  t>-pe  specimen,  from  Locality  303b,  Lower  Ordovician,  Etago 
dl,  in  the  envdrons  of  Rokitzan,  Bohemia,  showing  strong  radiating  stria?.     Copied  from  Barrande 
[1879b,  PI.  CXXVI,  fig.  ii:  hA]. 
46 


U.  S.   GEOLOGICAL  SURVEY 


MONOGRAPH   LI     PL.  XII 


FRANCES  WIESefi  DEL. 


KELIOTYPC    CO    SOSl 


PLATE  XII.  47 

Obolus?  (Westonia?)  lamellosus  (Barrande)  (p.  463). 

FiouEE  7.  Enlargement  of  a  dorsal  valve,  the  type  specimen.     Copied  from  Barrande  [1879b,  PI.  CVI,  fig.  i:  2A]. 
7a.  Surface  and  lamella;  of  shell  greatly  enlarged.     Copied  from  Barrande  [1879b,  PI.  CVI,  fig.  i:  3f]. 
7b.  Elongate  dorsal  valve.     Copied  from  Barrande  [1879b,  PI.  CXI,  fig.  ix:  2A]. 
7c.  Distorted  ventral  ?  valve.     Copied  from  Barrande  [1879b,  PI.  CXI,  fig.  i.x:  lA]. 

7d.  Enlargement  of  the  surface  of  the  specimen  represented  in  figure  7c.  Co]iie<l  from  Barrande  [lS79b,  PI. 
CXI,  fig.  ix:  If]. 

The  specimens  represented  are  all  from  Locality  303  1,  Lower  Ordo\ician,  Etage  dl,  Libetschov,  B(^llemia. 

Obolus  complexus  Barrande  (p.  3S7). 

fPl.  XII.  figs.  3  and  3a.] 

Figures  8  and  8'.  Cast  of  interior  and  side  outline  of  a  ventral  ?  valve  from  Locality  303i,  Lower  Ordovician,  Etage 
dl,  Kruschna  Hora,  Bohemia.     Copied  from  Barrande  [lS79b,  PI.  XCV,  figs,  in:  W  and  IB,  respec- 
tively]. 
8a.  Supposed  cast  of  interior  of  dorsal  valve  from  Locality  303h,  Lower  Ordovician,  Etage  dl,  Milinsky  Wrch, 
near  Woleschna,  Bohemia.     Copied  from  Barrande  [1879b,  PI.  XCV,  fig.  in:  2C]. 

Obolus  feistmanteli  (Barrande)  (]x  .391). 

IPl.XII,  figs.  1,  la-f.I 

9.  Cast  of  the  inner  surface  of  the  frontal  rim  of  the  shell,  greatly  enlarged.  Original  in  the  Museum  of  Com- 
parative Zoology;  cast  in  the  Ignited  States  National  Jluseuuf  (Cat.  No.  .'57088d). 

9a.  Traces  of  the  minute  terminal  vessels  that  cross  the  inner  surface  near  the  anterolateral  margins  of  the 
shell;  greatly  enlarged  from  a  portion  of  the  surface  of  the  specimen  represented  by  figure  le.  Original 
in  the  Museum  of  Comparative  Zoology;  cast  in  the  United  States  National  Museum  (Cat.  No.  57088c). 

The  specimens  represented  are  both  from  Locality  3031,  Lower  Ordovician  sandstone,  Etage  dl,  Kruschna  Hora, 
Bohemia. 


PLATE    XIII. 


62667°— VOL  51,  PT  2—12 1  49 


PLATE  XIII. 

Obolus  (Broggeria)  salteki  (Iloll)   (p.  424). 

[PI.  XV,  figs.  4,  4a-d.) 

Figure  1.  Exterior  of  ventral  valve  from  Locality  309i,  Upper  Cambrian  near  Sandby,  Province  of  Malmohus,  Sweden. 

U.  S.  Nat.  Mus.  Cat.  No.  51673a. 
la.  Ventral  valve  associated  with  the  specimen  represented  by  figure  1,  showing  a  cast  of  part  of  the  interior 

of  the  shell.     U.  S.  Nat.  Mus.  Cat.  No.  51673b. 
lb.  Cast  of  the  interior  of  a  dorsal  valve  associated  with  the  specimen  represented  by  figure  ].     U.  S.  Xat. 

Mus.  Cat.  No.  51673c. 
Ic.  Cast  of   the  interior  of  a  ventral  valve  from  Locality  3091,  Upper  Cambrian,  Sweden  (exact  locality 

unknown),  showing  the  area,  more  or  less  of  the  maui  vascular  .■^inuse.':,  and  the  visceral  cavity.     U.  S. 

Nat.  Mus.  Cat.  No.  5139Sa. 
Id.  Cast  of  the  interior  of  a  ventral  valve  from  Locality  101,  Upper  Cambrian  shales,  east  bank  of  BarachoLs 

River,  G  miles  from  Little  Bras  d'Or  Lake,  Cape  Breton,  Nova  Scotia.     U.  S.  Nat.  Mus.  Cat.  No. 

51671a. 

10.  Cast  of  the  interior  of  a  ventral  valve  from  Locality  3q,  L'pper  Cambrian  shale.?,  Barachois  Glen,  4   miles 

south  of  Little  Bras  d'Or  Lake,  Cape  Breton,  Nova  Scotia.     U.  S.  Nat.  Mus.  Cat.  No.  52441a. 

If.  Cast  of  the  interior  of  a  dorsal  valve  from  Locality  309 1,  L'pper  Cambrian,  Sweden  (exact  locality  unknown). 
U.  S.  Nat.  Mus.  Cat.  No.  5139Sb. 

Ig.  Cast  of  exterior  of  a  ventral  valve  from  Locality  lOi,  Upper  Cambrian  shales,  Barachois  River,  north  of 
Boisdale  road.  Cape  Breton,  Nova  Scotia,  with  a  portion  of  the  shell  covering  the  area  broken  away. 
U.  S.  Nat.  Mus.  Cat.  No.  52442a. 

Ih,  li,  and  Ij.  Casts  of  dorsal  valves  from  Locality  101,  Upper  Cambrian  shales,  cast  bank  of  Barachois  River, 
6  miles  from  Little  Bras  d'Or  Lake,  Cape  Breton,  Nova  Scotia,  varying  in  outline,  owing  to  compres- 
sion in  the  shale.     U.  S.  Nat.  Mus.  Cat.  Nos.  51671b,  51671c,  and  51671d,  respectively. 

Ik.  Cast  of  dorsal  valve  from  Locality'  Sq,  ITpper  Cambrian  shales,  Barachois  Glen,  4  miles  south  of  Little 
Bras  d'Or  Lake,  Cape  Breton,  Nova  Scotia.     L'.  S.  Nat.  Mus.  Cat.  No.  52441b. 

11.  Cast  of  dorsal  valve  from  Locality  101   Upper  Cambrian  shales,  Barachois  River,  north  of  Boisdale  road, 

Cape  Breton,  Nova  Scotia.     U.  S.  Nat.  Mus.  Cat.  No.  52442b. 

Im.  Cast  of  the  interior  of  a  dorsal  valve  from  Locality  323f,  Ceratopyge  limestone  at  \'estfossen,  10  miles 
west-southwest  of  Christiania,  Norway,  reproduced  from  a  photograph.  The  markings  of  the  vas- 
cular system  are  beautifully  preserved  in  the  cast.  L^niv.  Min.  Inst.  Christiania,  Norway.  Specimen 
illustrated  by  Brogger  [1S82,  PI.  X,  fig.  10]  as  Obolus  salteri. 

In.  Interior  of  a  ventral  valve  from  Locality  323w,  Upper  Cambrian  at  Christiania,  Norway,  flattened  in  shale. 
It  is  one  of  the  largest  shells  of  this  specie ;  known  to  the  author.    Univ.  Min.  Inst.  Christiania,  Norway. 

Obolus  (Acritis  0  rvgatu.s  Walcott  (p.  441). 

Figure  2.  Exterior  view  of  the  type  specimen  from  Locality  58,  Middle  Cambrian  Secret  Canyon  shale.  New  York 
and  Secret  canyons,  Eureka  district,  Nevada.     U.  S.  Nat.  Mus.  Cat.  No.  35229a. 

Obolus  (Acritis)  axtiquissimus  (Eichwald)  (p.  437). 

[I'l.  XV,  figs.  2,  2a-d.] 

Figure  3.  Surface  of  shell  enlarged  four  and  one-half  times.     Locality  396d,  passage  bed.s  between  the  Upper  Cambrian 
and  the  Ordovician,  "glauconite  limestone,"  at  Domglint,  in  Reval,  Esthonia,  Russia.     I'.  S.  Nat. 
Mus.  Cat.  No.  51534a. 
50 


U.  S.   GEOLOGICAL  SURVEY 


MONOGRAPH   LI     PL.  Xlll 


FRANCES  WlESEFt  DEL. 


MELIOTyPE   CO   BOSTON 


PLATE    XIV. 


51 


PLATE  XIV. 


c.  Trapezoidal  area,  Including  central,  middle 
lateral,  and  outside  lateral  muscle  scars, 
h.  Central  muscle  scar. 
i.  Transmedian  muscle  scar, 
j.  Anterior  lateral  muscle  .soar. 


I.  Outside  latt-ral  muscle  scar. 
vs.  Main  vascular  sinus, 
s.  Median  septum. 
.X.  Heart-shaped  cavity. 


Obolus  (Schmidti.v)  celatus  (\'olhorth)  (]>.  444). 


Specimen  figured  by  Walcott  [1898b,  PI.- 


Specimen  figured  by  Walcott  [1898b,  PI. 


Figure  1.     E.xterior  of  ventral  valve.     U.  S.  Nat.  Mus.  Cat.  No.  35237a. 
la.  Interior  of  ventral  valve.    U.  S.  Nat.  Mus.  Cat.  No.  3.5237b. 

XXVI,  fig.  1]  as  Obolus  (LinguJella)  celatus. 
lb.  Exterior  of  dorsal  valve.     U.  S.  Nat.  Mus.  Cat.  No.  35237c. 
Ic.  Interior  of  dorsal  valve.     U.  S.  Nat.  Mus.  Cat.  No.  35237d. 

XXVI,  fig.  2]  as  Obolus  (Lingulella)  celatus. 

The  specimens  represented  are  all  from  Locality  395,  Ujiper  Cambrian  Obolus  sandstone  at  Joa,  near  Jegelecht, 
Eathonia,  Russia. 

Obolus  (Schmidtia)  acitviinatus  Mickwitz  (p.  442). 

Figure  2.     Exterior  of  ventral  valve.     U.  S.  Nat.  Mus.  Cat.  No.  51531a. 
2a.  Interior  of  ventral  valve.     U.  S.  Nat.  Mus.  Cat.  No.  51531b. 
2b.  Exterior  of  dorsal  valve.     U.  S.  Nat.  Mus.  Cat.  No.  51.531c. 
2c.  Interior  of  dorsal  valve.     U.  S.  Nat.  Mus.  Cat.  No.  51531d. 

The  specimens  represented  are  all  from  Locality  395,  L'pper  Cambrian  Obolus  sandstone  at  Joa,  near  Jegelecht, 
Esthonia,  Russia. 

Obolus  (Schmidtia)  obtusus  Mickwitz  (p.  448). 

Figure  3.  Exterior  of  ventral  valve.  L'.  S.  Nat.  Mus.  Cat.  No.  51532a. 
3a.  Interior  of  ventral  valve.  U.  S.  Nat.  Mus.  Cat.  No.  51532b. 
3b.  Exterior  of  dorsal  valve.  V.  S.  Nat.  Mus.  Cat.  No.  51532c. 
3c.  Interior  of  dorsal  valve.     U.  S.  Nat.  Mus.  Cat.  No.  51532d. 


The  specimens  represented  are  all  fiotu  Luc 
Esthonia,  Russia. 


ilit\ 


395.  Upper  Cambrian  Obolus  sandslone  at  Joa,  near  Jegelecht, 

Obolus  (Schmidtia)  crassus  Mickwitz  (p.  446). 


Figure  4.     Exterior  of  ventral  valve.     U.  S.  Nat.  iliis.  Cat.  No.  51530a. 
4a.  Interior  of  ventral  valve.     U.  S.  Nat.  Mus.  Cat.  No.  51530b. 
4b.  Exterior  of  dorsal  valve.     I'.  S.  Nat.  Mus.  Cat.  No.  51530c. 
4c.  Interior  of  dorsal  valve.     U.  S.  Nat.  Mus.  Cat.  No.  51530d. 
4d.  Interior  of  an  elongate  form  of  a  dorsal  valve.     V.  S.  Nat.  Mus.  Cat.  No.  51530e. 

The  specimens  represented  are  all  from  Locality  395,  I'pper  Cambrian  Obolus  sandstone  at  Joa,  near  Jegelecht, 
Esthonia,  Russia.  . 

Lingulella  (Leptembolox)  linguljeformis  (Mickwitz)  (p.  542). 

Figure  5.     A  lai^e  dorsal  \ahe  from  Locality  396a,  pas.sage  lieds  between  the  I'pper  Cambrian  and  the  Ordovician, 
"glauconite  sandstone,"  at  Lejjpiko,  near  Leetz.  Esthonia,  Rtissia.     Copied  from  Mickwitz  [1896, 
PI.  Ill,  figs.  17a-b]. 
5a.  Small  dorsal  valve  associated  with  specimen  represented  by  figure  5b.     I".  S.  Nat.  Mus.  Cat.  No.  51537a. 
5b.  Small  ventral  valve  from  Locality  395,  Upper  Cambrian  0&o/»s  sandstone  at  Joa,  near  Jegelecht,  Esthonia, 
Russia.    The  beak  of  this  specimen  was  broken  awaj-  and  has  been  restored  in  outline  on  the  figure. 
U.  S.  Nat.  Mus.  Cat.  No.  51.537b. 
52 


U.  S.  GEOLOGICAL  SURVEY 


MONOGRAPH   LI     PL.  XlV 


PRANCES  WIESER  DEL. 


HEi,iOTr»e  CO  BOSTON 


PLATE  XIV.  53 

Obolus  apollinis  Eichwald  (p.  381). 

(Text  figs.  4,  p.  299,  and  1.5,  p.  299;  and  PI.  VII,  figs.  1-8, 10-17.) 

Figure  6.     Exterior  of  a  ventral  valve.     The  portion  of  the  frontal  margin  anterior  to  the  rrark  running  through  it  has 
been  restored. 
6a.  Exterior  of  a  dorsal  valve.     The  portion  of  the  frontal  margin  anterior  to  the  <ra(k  running  through  it  ha.s 
been  restored. 

The  specimens  represented  in  iigures  6  and  6a  can  not  now  be  located.  The  National  Museum  records  give 
the  locality  as  395,  Upper  Cambrian  Obolus  sandstone  at  Joa,  near  Jegelecht,  Esthonia,  Russia,  and  the  catalogue 
number  a.s  .51-52.5.     .Six  other  specimens  with  this  catalogue  number  are  figured  on  Plate  VII  of  this  monograph. 

Obolus  apollinis  maximus  Mickwitz  (p.  .384). 

(PI.  VII,  fig.  9.] 

Figure  7.  E.xterior  of  the  central  and  posterior  portions  of  a  dorsal  valve  that  illustrates  the  character  of  the  outer 
surface  of  the  numerous  layers  of  the  shell.  From  Locality  395,  Upper  Cambrian  Obolus  sandstone 
at  Joa,  near  Jegelecht,  Esthonia,  Russia.  U.  S.  Nat.  Mus.  Cat.  No.  .51528b. 
7a.  Partly  exfoliated  broken  ventral  valve,  showing  the  impression  of  the  main  vascular  sinuses  on  one  of 
the  inner  layers  of  the  shell,  also  the  laminated  character  and  interior  markings  of  the  shell.  From 
Locality  336j,  Upper  Cambrian  Obolus  sandstone  at  Staroja  Ladoga,  Government  of  Novgorod,  Russia. 
U.  S.  Nat.  Mus.  Cat.  No.  26924a. 


PLATE   XV. 


55 


PLATE  XV. 

h.  Central  muscle  scar.  j.  Anterior  lateral  muscle  scar. 

Obolus  (Mickwitzella)  siluricus  (Eichwald)  (p.  434). 

Figure  1.  Exfoliated  dorsal  valve.     U.  S.  Nat.  Mus.  Cat.  No.  51538a. 
la.  Exfoliated  ventral  valve.     U.  S.  Nat.  Mus.  Cat.  No.  51538b. 
lb.  Exterior  surface  of  shell.     Copied  from  Mickwitz  [1896,  PI.  Ill,  fig.  9]. 
Ic.  Enlargement  of  surface  of  ventral  valve.     U.  S.  Nat.  Mus.  Cat.  No.  51.538c. 

The  specimens  represented  are  all  from  Locality  396a,  passage  beds  between  the  Upper  Cambrian  and  the  Ordo- 
vician,  "glauconite  sandstone,"  at  Leppiko,  near  Leetz,  Esthonia,  Russia. 

Obolus  (Acritis)  axtiquissimus  (Eichwald)  (p.  4.37). 

I  PI.  XIII,  fig.  3.] 

Figures  2,  2a,  and  2b.  \'entral,  side,  and  dorsal  views  of  specimen  preserving  the  two  valves  nearly  united.  The 
outer  surface  of  the  shell  is  almost  entirely  exfoliated.     U.  S.  Nat.  Mus.  Cat.  No.  51534b. 

2c.  Photographic  enlargement  of  the  exterior  surface  of  the  .shell.     U.  S.  Nat.  Mus.  Cat.  No.  51534c. 

2d.  Exterior  of  a  partly  exfoliated  dorsal  valve,  with  the  side  outline  of  the  two  valves  united.  (_'opied 
from  Mickwitz  [1896,  PI.  Ill,  figs.  20a-b.] 

The  specimens  represented  are  all  from  Locality  396d,  passage  beds  between  the  Upper  Cambrian  and  the  Ordo- 
vician,  "glauconite  limestone,"  at  Domglint,  in  Reval.  Esthonia,  Russia. 

Obolus  elegans  Mickwitz  (p.  390). 

Figure  3.  Exterior  of  a  ventral  ?  valve  sho\ving  a  stronglj^  marked  surface.  Specimen  from  Locality  395b,  Upper 
Cambrian  Ohohis  sandstone  at  Ilgast.  Esthonia.  Russia.     U.  S.  Nat.  Mus.  Cat.  No.  5153.5a. 

Obolus  (Broggerl\)  salteri  (Holl)  (p.  424). 

ll'l.  XIII,  figs.  1,  la-n.] 

Figure  4.  Figure  of  ventral  valve,  the  type  specimen,  from  Locality  304e,  LTpper  Cambrian  "Black  shales"  at  Coal 

Hill,  Malvern  Hills,  England.     Copied  from  Holl  [1865,  p.  101,  fig.  0].     The  figure  was  also  copied 

by  Davidson  [1866,  PI.  IV,  figs.  28a  and  28]. 
4a  and  4b.  A'entral  and  dorsal  valves  occurring  in  Locality  310h.  Up]ier  Cambrian  dark  argillaceous  shale 

somewhere  in  Sk^ne  (Pro^^nces  of  Malmohus  and  Christianstad),  Sweden.     U.  S.  Nat.  Mus.  Cat. 

Nos.  14931a  and  14931b,  respectively. 
4c.  Cast  of  dorsal  valve  from  Locality  309j,  LTpper  Cambrian  argillaceous  shale  at  Alunbruk,  Oeland  Island, 

Sweden.     U.  S.  Nat.  Mus.  Cat.  No.  51676a. 
4d.  Partly  exfoliated  dorsal  valve  from  Locality  309h,  Upper  Cambrian  very  dark  siliceous  limestone  at 

Fogelsang,  Province  of  Malmohus,  Sweden.     U.  S.  Nat.  Mus.  Cat.  No.  51674a. 

Obolus  ?  palliatus  Barrande  (p.  407). 

Figure  5.  Exterior  surface  of  dorsal  valve,  the  type  specimen,  from  Locality  303c,  passage  beds  between  the  Cam- 
brian and  Ordovician,  in  the  suburbs  of  Ilof,  Bavaria,  Germany,  one-third  natural  size.  Copied 
from  Barrande  [lS68a,  fig.  65]. 

Obolus?  minor  Barrande  (p.  405). 

Figure  6.  Exterior  surface  of  ventral  valve,  the  type  specimen,  from  Locality  303c,  passage  beds  between  the  Vsim- 
brian  and  Ordovician,  in  the  suburbs  of  Ilof,  Bavaria.  Germany,  one-third  natural  size.  Copied 
from  Barrande  [1868a,  fig.  68], 

Acrotreta  inchoans  (Barrande)  (p.  690). 

Figures  7  and  7a.  Two  views  copied  from  Barrande  [1868a.  figs.  74  and  75]  of  shells  from  Locality  303c.  i>a,ssage 
beds  between  the  Cambrian  and  the  Ordovician,  suburbs  of  Ilof,  Bavaria,  Germany.     Figure  7  is 
the  type. 
56 


U.  S.  GEOLOGICAL  SURVEY 


MONOGRAPH  LI     PL.   XV 


">^rv. 


«'  # 


^^' 


V-    ^ 


\ 


10 

FRANCES  WIESER  DEL. 

J 


MCLIOTVPe    CO    BOSTON. 


,  PLATE  XV.  57 

Obolus?  sp.  undt.  e  Kayser  (p.  423). 

Figure  8.  Ventral  valve  associated  with  Eoorlhis  saltensis  in  Locality  389b,  Upper  Cambrian  sandstone  at  Tilcuya, 
Province  of  Jujuy,  Argentina.     Copied  from  Kayser  |!,S7(i,  PI.  I,  fig.  14]. 

Obolus?  sp.  undt.  f  Kayser  (p.  423). 

Figure  9.  Several  valves  on  small  fragment  of  limestone  from  Locality  332,  Upper  CamVjrian  at  Saimaki,  Liaotung, 
China.     Copied  from  Kayser  [1883,  PI.  Ill,  fig.  2]. 

Obolus  ?  ba various  (Barrand«)  (p.  385). 

Figure  10.  A'entral   valve,  the  type  specimen,  from  Locality  303c,  ]3as.sage  beds  between  the  Cambrian  and  Ordo- 
vician,  suburbs  of  Hof,  Bavaria,  Germany.     Copied  from  Barrande  [1868a,  fig.  02],  who  described 
it  as  Lingula  buvarica. 
10a.  Dorsal  valve  associated  with  the  shell  represented  by  figure  10  in  Locality  303c.     (Copied  from  Barrande 
[1868a,  fig.  61],  who  described  it  as  Obolus  f  palliatus. 

Obolus  schmidti  Mickwitz  (p.  412). 

FiGURE.s  lla-c.  Exterior,  side,  and  interior  views  of  a  dorsal  valve,  the  tj'pe  specimen,  from  Locality  39S,  Upper 
Cambrian  Obolus  sandstone  at  Joa,  near  Jegelecht,  Esthonia,  Russia.  (!'i.ipied  from  Mickwitz  [1896, 
PI.  II,  figs.  14a-c]. 

Obolus?  murrayi  Billings  (p.  405). 

Figure  12.  Figure  of  the  original  type  specimen  from  Locality  314g,  Lower  Ordovician,  Maiden  Arm,  Hare  Bay, 
northern  Newfoundland.  Geol.  Survey  Canada.  The  specimen  is  the  one  on  which  Billings  [186-5, 
p.  362]  based  his  species,  but  he  did  not  figure  it. 


PLATE   XVI. 


59 


PLATE  XVI. 


a.  Central  lateral  space  of  area, 
a'.  Outer  lateral  spai-e  of  area, 
c.  Trapezoidal  area,  including  central,  Tniddle 

lateral,  and  outside  lateral  muscle  scars, 
h.  Central  muscle  scar. 
J.  Transraedian  muscle  scar. 
j.  -\nterior  lateral  muscle  scar. 


k.  Middle  lateral  muscle  scar. 
1.  Outside  lateral  muscle  scar. 
p.  Pedicle  groove. 
V.  \'isceral  cavity. 
vs.  Main  vascular  sinus. 
X.  Heart-shaped  cavity. 


ObOLUS    (LiNGULOBOLl'S)  AFriNI.S   (BilHlliJ.s)    (p.  431). 

Figure  1.  Cast  of  the  interior  of  a  ventral  valve  showing  the  characteristic  visceral  cavity.     I".  S.  Nat.  Mus.  Cat. 

No.  51679a. 
la.  Cast  of  a  portion  of  the  interior  uf  a  ventral  valve.     V .  S.  Xat.  Mus.  (at.  No.  .51679b. 
lb.  Cast  of  the  interior  of  a  ventral  valve  showing  the  cast  of  the  deep  impressions  in  which  the  muscle  scars 

are  situated.     V.  S.  Nat.  Mus.  Cat.  No.  ,51679c. 
Ic.  Cast  of  the  interior  of  a  dorsal  valve  showing  the  iHisitioii  of  the  central  and  anterior  lateral  muscle  scars. 

U.  S.  Nat.  Mus.  Cat.  No.  51079<1. 
Id.  Partly  exfoliated  dorsal  valve  showing  the  area  and  the  varied  surface  "i  tlic  inner  layers  of  the  shell. 

U.  S.  Nat.  Mus.  Cat.  No.  51679e. 
le.  Outline  of  the  area  of  a  dorsal  valve.     V.  S.  Nat.  Mus.  Cat.  No.  ol679f. 

The  specimens  represented  are  all  from  Locality  114b,  Lower  Ordovician  sandstone,  1  mile  north  of  Lance  Cove, 
Great  Belle  Island,  Conception  Bay,  Newfoundland. 

Obolus  (Linguloboll's)  spissus  (Billings)  (\i.  43.2). 

(Pi.  XLII,llgs..-!,3a.l 

Figure  2.  Dorsal  valve  from  which  the  outer  layers  of  the  shell  have  been  exfoliated  so  as  to  show  the  outline  of  the 

visceral  cavity  and  vascular  sinuses.     L'.  S.  Nat.  Mus.  Cat.  No.  ,51678  1.     Part  of  the  inner  surface 

of  this  specimen  is  enlarged  on  Plate  XLII,  figure  3a. 
2a.  Cast  of  the  interior  of  a  dorsal  valve,  on  which  portions  of  the  shell  remain  over  the  muscle  scars.     I".  S. 

Nat.  Mus.  Cat.  No.  51678a. 
2b.  Dorsal  valve  preserving  a  portion  of  the  outer  surface   of  the  shell,  which  is  enlarged  in  Plate  XLII, 

figure  3.     U.  S.  Nat.  Mus.  Cat.  No.  51678b. 
2c.  Partly  exfoliated  dorsal  valve  showing  something  of  the  character  and  arrangement  of  the  inner  layers  of 

the  shell.     U.  S.  Nat.  Mus.  Cat.  No.  51678c. 
2d.  Partly  exfoliated  dorsal  valve  illustrating  how  the  impressions  of  the  vascular  sinuses  and  markings  are 

preserved  on  the  various  layers  of  the  shell.     L'.  S.  Nat.  Mus.  Cat.  No.  51678d. 
2e.  Inner  layers  of  the  central  portion  of  a  ventral  valve,  showing  the  characteristic  trapezoidal  area  and 

vascular  sinuses  of  Obolus.     U.  S.  Nat.  Mus.  Cat.  No.  51678e. 
2f.  Partly  exfoliated  dorsal  valve  illustrating  peculiarities  of  the  shell  not  shown  by  other  figures.     U.  S.Nat. 

Mus.  Cat.  No.  51678f. 
2g.  Cast  of  the  interior  of  a  dorsal  valve  with  vertical  and  transverse  outline  of  the  convexity  of  the  eheU. 

U.  S.  Nat.  Mus.  Cat.  No.  51678g. 
2h.  Partly  exfoliated  dorsal  valve  that  is  more  elongate  than  most  specimens.     V.  S.  Nat.  Mus.  Cat.  No.  51678h. 
2i.  An  unusually  well  preserved  ventral  valve,  showing  the  various  layers  frirming  the  shell.     U.  S.  Nat. 

Mus.  Cat.  No.  51678i. 
2j.  Interior  of  a  ventral  valve  as  shown  by  the  impression  made  on  the  laminated  inner  layers  of  the  shell, 

the  outer  layers  being  exfoliated.     V.  S.  Nat.  Mus.  Cat.  No.  51678J. 
2k.  Cast  of  the  interior  of  a  ventral  valve,  showing  muscle  scars  and  va.-^cular  markings  essentially  the  same 

as  those  of  Obolus.     V.  S.  Nat.  Mus.  Cat.  No.  51678k. 

The  specimens  represented  are  all  from  Locality  114b,  Lower  Ordovician  sandstone,  1  mile  north  <if  Lance  Cove, 
Great  Belle  Island,  Conception  Bay,  Newfoundland. 
60 


U.   S.   GEOLOGICAL  SURVEY 


MONOGRAPH    U     PL.  XVI 


FRANCES  WIESER  DEL. 


vpe  CO  aosTOM 


PLATE    XVII, 


61 


PLATE  XVII. 

a.  Tentral  laleral  space  of  area.  m.  Pedicle  muscle  scar, 
a'.  Outer  latenil  space  of  area.  p.  Pedicle  groove. 

c.  Trapezoidal   area,  including   central,  ps.  Parietal  band. 

middle  lateral,  and  outside  lateral  s.  Median  septum. 

muscle  scars.  v.  Visceral  cavity. 

f.  Fle.xure  line  of  area.  vs.  Main  vascular  sinus. 

g.  Umbonal  muscle  scar.  ivs.  Lateral  branches  of  vascular  system, 
h.  Central  muscle  scar.                                                   pvs.  Peripheral  branches   of  the  vascular 

i.  Transmedian  muscle  scar.  system, 

j.  Anterior  lateral  muscle  scar.  x.  Heart-shaped  cavity, 

k.  Middle  lateral  muscle  scar.  z.  Same  as  ivs  of  the  ventral  valve. 

I.  Outside    lateral   and    middle   lateral 
muscle  scars. 

LiNGULELLA  ACUTANGULA  (Roemcr)  (p.  474). 

Figure  1.  Ventral  valve  in  limestonp,  from  which  the  shell  is  partly  exfoliated.     Locality  69,  Upper  Cambrian, 

Honey  Creek,  Burnet  County,  Texas.     V.  S.  Nat.  Mus.  Cat.  No.  27412a.     The  area  of  this  shell  is 

enlarged  in  figure  Irl. 
la.  Cast  of  the  interior  of  a  ventral  valve  from  Locality  353c,  Upper  Cambrian  sandstone,  Llano  County,  Texas, 

showing  concentric  lines  of  tubercles  that  fill  the  punctae  of  the  interior  surface  of  the  shell.     U.  S. 

Nat.  Mus.  Cat.  No.  35240a.     The  area  of  this  shell  is  enlarged  in  figure  lb. 
lb.  Enlargement  of  cast  of  area  and  pedicle  groove  of  figure  la.     U.  S.  Nat.  Mus.  Cat.  No.  35240a. 
Ic.  Cast  of  interior  of  ventral  valve,  from  same  locality  as  the  specimen  represented  in  figiu-cs  la  and  lb,  in 

which  the  cast  of  the  \-isceral  cavity  and  muscle  scars  is  unusually  prominent.     V.  S.  Nat.  Mus.  Cat. 

No.  3.5240b.     Copied  from  Walcott  [1898b,  PI.  XX\'II,  fig.  6]. 
Id.  Enlargement  of  the  cast  of  the  area  of  the  specimen  represented  by  figure  1.     V.  S.  Nat.  Mus.  Cat.  No. 

27412a. 
le.  Ventral  valve  in  sandstone  from  Locality  68,  Upper  Cambrian,  Packsaddle  Mountain,  Llano  County, 

Texas.     U.  S.  Nat.  Mus.  Cat.  No.  27410a. 
If.  Cast  of  the  interior  of  a  ventral  valve  showing  the  muscle  scars  unusually  well  preserved.     Locality  353c, 

Upper  Cambrian  sandstone,  Llano  County,  Texas.     U.  S.  Nat.  Mus.  Cat.  No.  35240c.     Copied  from 

Walcott  [1898b,  PI.  XXVIII,  fig.  1]. 
Ig.  Cast  of  the  interior  of  a  ^•entral  valve  from  Locality  69,  Upper  Cambrian  limestone.  Honey  Creek,  Bimiet 

County,  Texas.     U.  S.  Nat.  Mus.  Cat.  No.  27412b. 
Ih.  Cast  of  the  interior  of  a  dorsal  valve  from  Locality  3f-3c,  Upper  Cambrian  sandstone,  Llano  County,  Texas, 

in  which  the  interior  lateral  branches  (?.)  of  th  >  vascular  system  are  shown.     U.  S.  Nat.  Mus.  Cat. 

No.  35240d.     Copied  from  Walcott  [189Sb,  PI.  XXVIII,  fig.  2]. 
li.  Cast  of  the  interior  of  a  dorsal  valve  from  Locality  69,  Upper  Cambrian  limestone,  Honey  Creek,  Burnet 

County,  Texas.     U.  S.  Nat.  Mus.  Cat.  No.  27412c. 
Ij.  Cast  of  the  interior  of  a  dorsal  valve  which  shows  that  the  punctate  surface  of  the  interior  of  the  shell  did 

not  extend  to  the  outer  border.     From  Locality  353c,  tapper  Cambrian  sandstone,  Llano  County, 

Texas.     U.  S.  Nat.  Mus.  Cat.  No.  35240e. 
Ik.  Cast  of  the  interior  of  a  dorsal  valve  from  Localitj-  68e,  Upper  Cambrian  sandy  limestone,  Packsaddle 

Mountain,  Llano  County,  Texas.     U.  S.  Nat.  JIus.  Cat.  No.  27410b. 
11.  Enlargement  of  a  portion  of  a  ventral  valve  showing  the  outer  surface  in  front  of  the  line  a"  a"  and  the 

surface  of  one  of  the  inner  layers  of  the  shell  back  of  a"  a".     I'.  S.  Nal.  Mus.     The  specimen  from 

which  this  figure  was  drawn  can  not  be  located;  even  the  locality  is  unknown. 
Im.  Median,  longitudinal,  thin  section  through  the  central  portion  of  a  ventral  ^alve;  os=thin  outer  layer 

without  traces  of  structure;  is=obliquely  laminated  inner  layer;  il=interior  lamellas  produced 

by  the  thickening  of  the  shell.     U.  S.  Nat.  Mus.  Cat.  No.  27410c. 
In.  Central  portion  of  a  transverse  median  thin  section;  os=thin  outer  layer;  i.«=obliquely  laminated  inner 

layer.     U.  S.  Nat.  Mus.  Cat.  No.  27410d. 
lo.  Median  longitudinal  section  through  the  posterior  portion  of  a  vintral  valve.     Lettering  same  as  for  figure 

Im.     U.  S.  Nat.  Mus.  Cat.  No.  27410e. 

The  specimens  thin-sectioned  for  reproduction  in  figures  Im,  In,  and  lo  came  from  I.cnality  68e,  Upper  Cambrian 
sandy  limestone,  Packsaddle  Mountain,  Llano  County,  Texas. 
62 


U.  S.   GEOLOGICAL  SURVEY 


MONOGRAPH   LI     PL.  XVII 


FRANCES  WtESEH  DEL. 


HEUIQTYPC   CO   aOSTOM 


PLATE   XVIII. 


63 


PLATE  XVIII. 

a.  Central  lateral  space  of  area.  j.  Anterior  lateral  muscle  scar, 

a'.  Outer  lateral  space  of  area.  p.  Pedicle  groove, 

f.  Flexure  line  of  area.  v.  Visceral  cavity. 

h.  Central  muscle  scar.  vs.  Main  vascular  sinu^. 

LlNGULELL.A.   MOSI.V    (Hall)     (p.  5'2()). 

Figure  1.  Cast  showing  part  of  the  interior  of  a  ventral  valve  from  Locality  85s,  Tppt-r  <  ambrian  sandstone  at  Prairie 

du  Sac,  Wisconsin.     U.  S.  Nat.  Miis.  Cat.  No.  27370a. 
la.  Cast  of  a  compressed  ventral  valve  from  Locality  85x,  I'pper  Camliriaii  sandstone  near  Mazomanie, 

Wisconsin.    U.  S.  Nat.  Mus.  Cat.  No.  27373a. 
lb.  Cast  of  a  ventral  valve  from  Locality  78s,  L^pper  Cambrian  sandstone  in  suburbs  of  Osceola,  Wisconsin. 

U.  S.  Nat.  Mils.  Cat.  No.  27371a. 
Ic.  Cast  of  the  interior  of  a  compressed  specimen  of  a  ventral  valve,  showing  traces  of  the  interior  markings. 

Locality  S85x,  I'pper  Cambrian  sandstone  near  Jlazomanie,  Wisconsin.     U.  S.  Nat.  Mus.  Cat.  No. 

27373b. 
Id.  Cast  of  the  interior  of  a  dorsal  valve  from  Locality  78s,  L'pper  Cambrian  sandstone  near  Osceola,  ^\'b- 

consin.     U.  S.  Nat.  Mus.  Cat.  No.  27371b. 
le.  Cast  of  a  more  elongate  dorsal  valve  from  Locality  78,  Upper  Cambrian  sandstone  near  Osceola,  \\'is- 

consin.     L'.  S.  Nat.  Mus.  Cat.  No.  27371c. 
If.  Cast  of  a  dorsal  valve  that  is  much  broader  posteriorly  than  most  dorsal  valves  of  the  species.     Locality  86, 

L'pper  Cambrian  sandstone  at  Gibraltar  Bluff,  Lodi,  Wisconsin.     U.  S.  Nat.  Mus.  Cat.  No.  27372a.     A 

specimen  from  Locality  S85x  (Cat.  No.  27373c)  was  used  to  restore  portions  of  this  figiu'e. 

LiNGULELLA    MOSIA    OSCEOLA    (Walcott)    (p.  521). 

Figure  2.  Cast  of  a  ventral  valve,  the  type  specimen,  from  Locality  78,  L'pper  Cambrian  sandstone  near  Osceola, 

Wisconsin.     I^.  S.  Nat.  Mus  Cat.  No.  27327a. 
2a.  Cast  of  ventral  valve  from  Locality  78s,  Upper  Cambrian  sandstone  near  Osceola,  Wisconsin.     U.  S.  Nat. 

Mus.  Cat.  No.  27327b. 
2b.  Enlargement  of  the  area  of  the  cast  of  a  ventral  valve,  associated  with  the  specimen  represented  by  figure  2. 

U.  S.  Nat.  Mus.  Cat.  No.  27327c 
2c.  Cast  of  a  dorsal  valve  associated  with  the  ventral  valve  represented  by  figure  2      U.  S.  Nat.  Mus.  Cat.  No. 

27327d. 

LiNGULELLA   WINOXA    (Hall)   (p.  539). 

Figure  3.  Cast  of  ventral  valve  from  Locality  78c,  L'pper  Cami>riau  sandstone  at  O.'sceola,  Wisconsin.  I'.  S.  Nat. 
Mus.  Cat.  No.  27400a. 

3a.  Partly  exfoliated  ventral  ^■alve  from  Locality  85s,  l'pper  Cambrian  sandstone  at  Prairie  du  Sac,  Wis- 
consin.    U.  S.  Nat.  Mus.  Cat.  No.  33856a. 

3b.  Partly  exfoliated  dorsal  valve,  associated  with  the  specimen  represented  by  figure  3a.  I'.  S.  Nat.  Mus. 
Cat.  No.  33856b. 

LiNGULELLA    WINOXA    CONVEXA    (Walcott)     (p.  540). 

Figure  4.  Two  ventral  valves,  natural  size,  from  Locality  S85x,  Upper  Cambrian  sandstone  near  Mazomanie, 
Wisconsin.     U.  S.  Nat.  Mas.  Cat.  No.  51854a. 

4a  and  4b.  Casts  of  \entral  valves  showing  area.  Locality  78,  Upper  Cambrian  sandstone  near  t)sceola. 
Wisconsin.  L'.  S.  Nat.  Mus.  Cat.  Nos.  3523-5a  and  3.5235b,  respectively.  Figure  4a  represents  the 
type  specimen. 

4c.  Cast  of  the  usual  form  of  dorsal  \al\e.  Same  locality  as  specimen  represented  by  figure  4a.  U.  S.  Nat. 
Mus.  Cat.  No.  35235c. 

4d.  Cast  of  an  elongate  form  of  dorsal  valve,  showing  central  and  anterior  lateral  Bcaxa.    Same  locality  as  speci- 
men represented  by  figure  4a.     U.  S.  Nat.  Mus.  Cat.  No.  3.5235d. 
64 


U.  S.  GEOLOGICAL  SURVEY 


MONOGRAPH   LI     PL.  XVIl- 


FRANCES  WIESER  DEL. 


MELIOTVf'E     CO     OOSTOw 


PLATE  XVIII.  65 

LlKGULELLA    OWENI    (Walcott)    (p.     523). 

FiouHE  5.  Ventral  valve  showing  the  exterior  surface  of  the  shell,  from  Locality  86,  Upper  Cambrian  sandstone  at 

Gibraltar  Bluff,  Lodi,  Wisconsin.     U.  S,  Nat.  Mus.  Cat.  No.  25330a. 
5a.  Enlargement  of  the  area  of  a  cast  of  a  flattened  ventral  valve  in  which  all  traces  of  a  flexure  line  have  been 

lost.     Locality  86s,  Upper  Cambrian  sandstone  at  Prairie  du  Sac,  Wisconsin.     U.  S.  Nat.  Mus.  Cat. 

No.  27385a. 
5b.  Cast  of  the  interior  of  a  dorsal  valve,  the  type  specimen,  associated  with  the  specimen  represented  by 

figure  5.    U.  S.  Nat.  Mus.  Cat.  No.  25330b. 
5c.  A  smaller  and  less  elongate  dorsal  valve  than  that  represented  by  figure  5b,  but  from  the  same  locality. 

U.  S.  Nat.  Mus.  Cat.  No.  25330c. 
5d  and  5e.  Casts  of  small  ventral  valves  from  Locality  78c,  Upper  Cambrian  sandstone  at  Osceola,  Wis- 
consin.    U.  S.  Nat.  Mus.  Cat.  Nos.  27329a  and  27329b,  respectively.  . 
5f.  Cast  of  a  dorsal  valve  from  same  locality  as  specimens  represented  by  figures  5d  and  5e.     U.  S.  Nat.  Mus. 

Cat.  No.  27329c. 

Obolus  discoideus   (Hall  and  Whitfield)  (p.  389). 

Figure  6.  Exteriorof  a  partly  exfoliated  ventral  valve.     U.  S.  Nat.  Mus.  Cat.  No.  24555a. 

6a.  Dorsal  valve,  partly  exfoliated.     U.  S.  Nat.  Mus.  Cat.  No.  245.55b. 

6b  and  6c.  Probably  ventral  valves,  but  it  is  difficult  to  determine  owing  to  the  rounding  of  the  posterior 
portion  of  the  valve.  V.  S.  Nat.  Mus.  Cat.  Nos.  24555c  and  24555d,  respectively.  Figure  6c  is  drawn 
from  the  type  specimen  figured  by  Hall  and  WTiitfield  [1877,  PI.  I,  fig.  2].  The  specimen  repre- 
sented by  their  figure  1  is  not  redrawn  in  this  monograph. 

The  specimens  represented  by  figures  6,  6a-c  are  all  from  Locality  313j,  Upper  Cambrian  limestone  in  the  Eureka 
district,  Nevada. 

Figure  6d.  Partly  exfoliated  dorsal  valve,  showing  outline  of  visceral  area,  from  Locality  62,  Upper  Cambrian 
Dunderberg  shale,  north  of  Adams  HUl,  Eureka  district,  Nevada.     U.  S.  Nat.  Mua.  Cat.  No.  51547a. 
62667°— VOL  51,  pt  2—12 5 


PLATE    XIX. 


67 


PLATE  XIX. 

h.  Central  muscle  scar.  v.  Visceral  cavity. 

j.    Anterior  lateral  muscle  scar.  vs.  Main  vascular  sinus. 

s.   Median  septum. 

LiNGULELLA    BELLULA    (Walcott)    (p.  482). 

FiGURR  1.  Cast  of  a  ventral  valve  from  Locality  114,  Upper  Camlirian  upper  sandstone  beds  of  Little  Belle  Island, 

Conception  Bay,  Newfoundland.     U.  S.  Nat.  Mus.  Cat.  No.  27309a. 
la.  Cast  of  the  interior  of  a  small  ventral  valve,  the  type  epecimen,  from  Locality  114a,  Upper  Cambrian 

arenaceous  shales  about  50  feet  below  the  sandstone  of  Locality  114,  Little  Belle  Island,  Conception 

Bay,  Newfoundland.     U.  S.  Nat.  Mus.  Cat.  No.  r)7082a. 
lb.  Cast  of  the  interior  of  a  ventral  valve  associated  with  the  specimen  represented  by  figure  la.    U.  S.  Nat. 

Mus.  Cat.  No.  57082b. 
Ic.  Cast  of  the  interior  of  a  dorsal  valve,  showing  the  arching  of  the  parietal  band  outward  to  the  main  vascular 

sinus,  associated  in  the  shale  with  specimen  represented  by  figure  la.     U.  S.  Nat.  Mus.  Cat.  No.  57082c. 
Id.  Cast  of  the  interior  of  a  dorsal  valve,  showing  the  median  septum  and  what  may  be  the  central  muscle 

scars,  associated  in  the  shale  with  specimen  represented  by  figure  la.     U.  S.  Nat.  Mus.  Cat.  No.  57082d. 
le.  Interior  of  a  dorsal  valve  associated  with  the  specimen  represented  by  figure  la.    U.  S.  Nat.  Mus.  Cat. 

No.  57082e. 

LiNGULELLA    BELLA    (Walff)tt)   (j).  481). 
[PI.  XXXVI,  fig.  4.] 

FiciuRE  2.  Cast  of  the  interior  of  a  ventral  valve  from  Locality  114a,  Upper  Cambrian  arenaceous  shale  beneath  tho 

upper  sandy  beds  on  Little  Belle  Island,  Conception  Bay,  Newfoundland.     U.  S.  Nat.  Mus.  Cat.  No. 

27307a. 
2a.  Cast  of  the  interior  of  a  ventral  valve,  associated  with  specimen  represented  by  figure  2,  but  which  is 

more  strongly  marked  by  concentric  and  radiating  striae.    U.  S.  Nat.  Mus.  Cat.  No.  27307b. 
2b.  Cast  of  the  interior  of  a  dorsal  valve,  the  area  of  which,  owing  to  fracture,  slightly  resembles  the  area  of  a 

ventral  valve.     From  the  same  bed  and  locality  as  specimen  represented  by  figure  2.     Y.  S.  Nat. 

Mus.  Cat.  No.  27307c. 
2c.  A  somewhat  broader  dorsal  valve  than  that  represented  by  figure  2b,  but  associated  in  the  same  bed  with 

it.     U.  S.  Nat.  Mus.  Cat.  No.  27307d. 
2d.  Cast  of  the  interior  of  a  ventral  valve  from  Locality  114b,   Lower  Ordovician  sandstone  1  mile  north  of 

Lance  Cove,  Great  Belle  Island,  Conception  Bay,  Newfoundland.     U.  S.  Nat.  Mus.  Cat.  No.  27308a. 
2e.  Finely  preserved  dorsal  valve,  associated  in  the  same  bed  with  specimen  represented  by  figure  2d.     U.  S. 

Nat.  Mus.  Cat.  No.  27308b. 
2f.  Cast  of  the  interior  of  a  convex  ventral  valve  from  Locality  114,  Upper  Cambrian  upper  sandstone  beds 

of  Little  Belle  Island,  Conception  Bay,  Newfoundland.     IT.  S.  Nat.  Mus.  Cat.  No.  57081a. 
2g.  Enlargement  of  a  cast  of  the  area  of  a  dorsal  valve,  associated  in  the  bed  with  specimens  represented  by 

figures  2d  and  2e.     U.  S.  Nat.  Mus.  Cat.  No.  27308c. 
2h.  Finely  preserved  ventral  and  dorsal  valves  from  which  the  thin  outer  surface  has  been  exfoliated,  the 

type  specimen,  associated  in  the  same  bed  with  specimen  represented  by  figure  2d.     U.  S.  Nat.  Mus. 

Cat.  No.  27308d. 
2i.  Dorsal  valve  from  Locality  114b,  see  figure  2d.     U.  S.  Nat.  Mus.  Cat.  No.  27308e. 
2j.  Cast  of  the  interior  of  a  ventral  valve,  natural  size,  from  Locality  114b,  see  figure  2d.     U.  S.  Nat.  Mus. 

Cat.  No.  27308f. 
2k  and  21.  Exterior  of  ventral  valves  from  Locality  114b,  sec  figure  2d.     U.  S.  Nat.  Mus.  Cat.  Nos.  27308g 

and  27308h,  respectively. 
2m.  Dorsal  valve.  U.  S.  Nat.  Mus.  Cat.  No.  27308i. 
2n.  D.irsal  valve.  V.  S.  Nat.  Mus.  Cat.  No.  27308J. 
2o.  Dorsal  valve.  U.  S.  Nat.  Mus.  Cat.  No.  27308k. 
2p.  Dorsal  valve.  U.  S.  Nat.  Mus.  Cat.  No.  27.308  1. 
2q.  Dorsal  valve.     U.  S.  Nat.  Mus.  Cat.  No.  27308m. 

Figures  2i,  2m-q  illustrate  variations  in  the  size  and  outline  of  dorsal  valves  from  LiH-ality  114b,  Lower  Ordovician 
sandstone,  1  mile  north  of  Lance  Cove,  Great  Belle  Island,  Conception  Bay,  Newfoundland. 
08 


o    S.  GEOLOGICAL  SURVEY 


MONOGRAPH   LI     PL.  XIX 


FRANCES  WIE3ER  DEL. 


PLATE  XIX.  69 

LiNGULELLA    ELLSI    (Walcott)   (j).  49.5). 

Figure  3.  Ventral  valve,  the  type  specimen,  slightly  distorted  by  compressidn,  showing  the  area.    11.  S.  Nat.  Miis.  <]at. 

No.  2731.5a. 
3a.  Cast  of  a  ventral  valve,  .showing  the  area  and  outlines  of  the  visceral  cavity.     U.  S.  Nat.  Mus.  Cat.  No. 

27315b. 
3b.  Dorsal  valve  crushed  down  into  the  ventral  valve.     U.  S.  Nat.  Mus.  Cat.  No.  2731.5c. 
3c.  Dorsal  valve  slightly  distorted  by  compression.     U.  S.  Nat.  Mus.  Cat.  No.  2731.5d. 

The  specimens  represented  are  all  from  Locality  220a,  Ordovician  .siliceou.s  shales  at  the  Grand  Trunk  railroad 
bridge  over  Chaudiere  River,  Quebec,  Canada. 

LiNGULELLA  L^vis  Mattliew   (p.  512). 

Figure  4.  A  large  dorsal  valve,  the  type  specimen.     University  of  Toronto,  Canada.     Specimen  figured  by  Ma'thew 

[1892,  PI.  XII,  fig.  4b], 
4a.  Ventral  valve  flattened  in  .shale.     University  of  Toronto,  Canada.     Specimen  figured  by  Matthew  [1892, 

PI.  XII,  fig.  4a]. 
4b.  Ventral  valve  flattened  in  the  shale.     University  of  Toronto,  Canada. 

The  specimens  represented  are  all  from  Locality  301n,  Upper  Cambrian  shales  near  the  falls  at  St.  John,  New 
Brunswick. 

LiNGULELLA  L^vis  GRANDis  Matthew  (p.  .512). 

Figure  4c.  Ca.st  of  the  interior  of  a  dorsal  valve  from  Locality  325b,  Upper  Cambrian  shale  at  Escasonie  Shore,  East 
Bay,  Cape  Breton,  Nova  Scotia.  University  of  Toronto,  Canada.  Specimen  figured  by  Matthew 
[1903,  PI.  XV,  fig.  Id]. 

LiNGULELLA    (LiNGULEPis)    SPATULA    (Walcott)    (]).  5.58). 

Figure  .5.  Nearly  perfect  ventral  valve,  the  type  specimen,  from  which  the  outer  surface  has  been  exfoliated.     U.  S. 

Nat.  Mus.  Cat.  No.  35290a. 
5a.  Dorsal  valve  preserving  concentric  and  radiating  stria?  beneath  the  outer  stirface.     U.  S.  Nat.  Mus.  Cat.  No. 

35290b. 
5b.  Cast  of  the  dorsal  valve,  showing  cast  of  median  ridge  and  pits  on  the  inner  surface.     U.  S.  Nat.  Mus.  Cat. 

No.  35290c. 

The  specimens  represented  are  all  fr<]ni  Locality  74d,  Middle  (^ambrian  sandstones  in  Bass  (."anyon.  Grand  Canyon 
of  the  Colorado,  Arizona. 


PLATE    XX. 


71 


PLATE  XX. 

h.  Central  muscle  scar.  v.  Visceral  cavity. 

j.  Anterior  lateral  muscle  scar.  •  vs.  Main  vascular  sinus. 

8.  Median  septum.  x.  Ilearl-sliaped  cavity. 

LlNGULELLA    MANTICULA    (Wllite)    (p.  517). 

Figure  1.  Cast  of  the  interior  of  a  ventral  valve  from  Locality  313f,  Upper  Cambrian  limestone  at  Schellboume, 

Schell  Creek  Range,  Nevada.     U.  S.  Nat.  Mus.  Cat.  No.  8569a. 
la.  Dorsal  valve  associated  on  the  same  hand  specimen  with  the  valve  represented  by  figure  1.     I'.  .S.  Xat. 

Mus.  Cat.  No.  85G9b. 
lb.  <'a8t  showing  part  of  the  interior  of  a  more  elongate  dorsal  valve  than  that  represented  by  figure  la,  but 

associated  on  the  same  hand  specimen  with  it.     U.  S.  Nat.  Mus.  Cat.  No.  8569c. 
Ic.  Type  specimen,  the  ventral  valve,  from  the  locality  represented  by  figures  1,  la-l>.     l'.  S.  Nat.  Mus. 

Cat.  No.  8569d.     When  the  plates  were  made  up  this  specimen  could  not  be  located  and  the  original 

drawing  prepared  for  White  [1877,  PL  III,  fig.  2b]  was  used.     The  specimen  has  been  found  on  the 

same  hand  specimen  with  the  type  of  Acrotreta  pyxidicula. 

Obolus  rotundatus  (Walcott)  (p.  411). 

Figure  2.  A  ventral  valve,  the  type  specimen,  from  Locality  313d,  Lower  Ordovician  limestone  near  Schellboume, 

Schell  Creek  Range,  Nevada.     U.  S.  Nat.  Mus.  Cat.  No.  27337a. 
2a.  Cast  of  the  interior  of  a  dorsal  valve  associated  with  the  shell  represented  by  figure  2.     U.  S.  Xat.  Mus. 

Cat.  No.  27337b. 
2b.  Ventral  valve  from   Locality  160a,  I'pper  Cambrian  limestone,  west  of  Bear  Creek,  south  of  (Jallatin 

Valley,  Montana.     IT.  S.  Nat.  Mus.  Cat.  No.  27338a. 
2c.  A  small  but  very  perfect  ventral  valve  associated  with  the  valve  represented  by  figure  2b.     V .  S.  Nat. 

Mus.  Cat.  No.  27338b. 
2d.  A  small  and  characteristic  dorsal  valve  associated  with  the  valves  represented  by  figures  2b  and  2c.     U.  iS. 

Nat.  Mus.  Cat.  No.  27338c. 
2e.  Dorsal  valve  from  Locality  302b,  Middle  Cambrian  limestones  near  Crowfoot  Ridge,  Yellowstone  National 

Park,  Wyoming.     U.  S.  Nat.  Mus.  Cat.  No.  35207a.     Specimen  figured  by  W'alcott  [1899,  PI.  LX, 

fig.  2a]  as  the  dorsal  valve  of  Obolus  (Lingulella)  desideratus.     (See  description  of  fig.  4,  below.) 

LiNGULELLA   POGONIPENSIS    (Walcott)    (p.  525). 

Figure  3.  Ventral  valve,  the  type  specimen,  showing  cast  of  the  area  and  the  pedicle  furrow.     U.  S.  Xat.  Mus. 
Cat.  No.  27332a. 
3a.  Small,  partly  exfoliated  ventral  valve.     U.  S.  Nat.  Mus.  Cat.  No.  27332b. 
3b.  Partly  exfoliated  dorsal  valve.     U.  S.  Nat.  Mus.  Cat.  No.  27332c. 
3c.  Partly  exfoliated  ventral  valve.     U.  S.  Nat.  Mus.  Cat.  No.  27332d. 
The  specimens  represented  are  all  from  Locality  201,  passage  beds  between  the  Upper  Cambrian  and  the 
Ordovician,  in  the  ridge  east  of  Hamburg  Ridge,  Eureka  district,  Nevada. 

Lingulella  desiderata  (Walcott)  (p.  492). 

Figure  4.  Partly  exfoliated  ventral  valve  from  Locality  302  I,  Upper  Cambrian  limestone,  Gallatin  Range,  Yellow- 
stone National  Park,  Wyoming.  U.  S.  Nat.  Mus.  Cat.  No.  33867a.  Type  specimen,  figured  by 
Walcott  [1899,  PI.  LX,  fig.  2]  as  Obolus  (Lingulella)  desideratus.     (See  description  of  fig.  2e,  above.) 

4a.  Dorsal  valve,  associated  with  the  specimen  represented  by  figure  4.     U.  S.  Nat.  Mus.  Cat.  No.  33S67b. 

4b  and  4c.  Ventral  and  dorsal  valves  on  the  ,'iamo  piece  of  limestone  from  Locality  81,  Upper  Cambrian,  near 
the  Hamburg  mine.  Eureka  district,  Nevada.  U.  S.  Nat.  Mus.  Cat.  Nos.  27313a  an<l  27313b, 
respectively. 

5  and  5a.  Ventral  valves  from  Locality  94xx,  Middle  Cambrian  shaly  limestones  at  Givens  Mill,  on  Cowan 
Creek,  Cherokee  County,  Alabama.     U.  S.  Nat.  Mus.  Cat.  Nos.  27355a  and  27355b,  respectively. 

5b.  Ventral  valve  from  Locality  93o,  Upper  Cambrian  shales  near  Jordans,  on  Cowan  Creek,  Cherokee 
Covmty,  Alabama.     U.  S.  Nat.  Mus.  Cat.  No.  56990a. 

5c.  Dorsal  valve,  slightly  distorted  in  outline,  from  Locality  94o,  Upper  Cambrian  shale  near  Givens  Ford, 
on  Cowan  Creek,  Cherokee  County,  Alabama.    U.  S.  Nat.  Mus.  Cat.  No.  56991a. 
72 


U.  S.   GEOLOGICAL  SURVEY 


MONOGRAPH   LI     PL.  XX 


FRANCES  WIESER  DEL. 


L'OTVPt     CO    006TON 


PLATE  XX.  73 

LiNGXiLELLA  DESIDERATA   (Walcott) — Continued. 

Figure  5d.  X'entral  valve  from  Locality  96,  Upper  Cambrian  limestone  near  Rome,  Floyd  County,  Georgia,  marked 

by  unusually  strong  concentric  striae.     U.  S.  Nat.  Mus.  Cat.  No.  51823a. 
5e.  Dorsal  valve  associated  with  the  ventral  valve  illustrated  by  figure  5d.     U.  S.  Nat.  Mus.  Cat.  No.  51823b. 
5f  and  5g.  Dorsal  valves  from  Locality  107a,  Upper  Cambrian  shaly  limestone  near  Copper  Ridge,  11  miles 

northwest  of  Knoxville,  Tennessee.     U.  S.  Nat.  Mus.  Cat.  Nos.  27312a  and  27312b,  respectively. 
5h.  Large  ventral  valve  from  Locality  93,  I'pper  Cambrian  shales  near  Jordans  on  Cowan  Creek,  Cherokee 

County,  Alabama,  referred  to  this  species  with  some  doubt.     U.  S.  Nat.  Mus.  Cat.  No.  56990b. 
5i.  Broad  dorsal  valve  from  Locality  93a,  Upper  Cambrian  shales  on  the  Terrapin  Creek  road  from  Center  to 

Amberson,  Cherokee  County,  Alabama,  that  is  doubtfully  referred  to  this  species,  although  there 

is  considerable  difference  in  the  form  of  the  shell  in  most  localities  at  which  it  occurs.     U.  S.  Nat. 

Mus.  Cat.  No.  51841a. 
5j.  Form  similar  to  that  in  figure  5i,  from  Locality  302b,  Upper  Cambrian  limestone  near  Crowfoot  Ridge, 

Yellowstone  National   Park,  Wyoming.     U.  S.  Nat.  Mus.  Cat.  No.  27311a.     Specimen  figured  by 

Walcott  [1899,  PI.  LX,  fig.  3]  as  Dicellomus  nanus. 

LlNGULELLA    PUNCTATA    (Walcott)    (p.  528). 

Figure  6.  Partly  exfoliated  ventral  valve  from  Locality  58,  Middle  Cambrian  Secret  Canyon  shale,  Secret  and  New 
York  canyons,  Eureka  district,  Nevada,  showing  cast  of  part  of  the  interior  surface  of  the  shell.  U.  S. 
Nat.  Mus.  Cat.  No.  27335a.  Type  specimen,  figured  by  Walcott  [1884b,  PL  IX,  fig.  3]  as  Lingulaf 
manticula. 
6a.  Parti v  exfoliated  dorsal  valve  associated  in  the  same  piece  of  limestone  with  the  specimen  represented 
by  figure  6.  U.  S.  Nat.  Mus.  Cat.  No.  27335b.  Specimen  figured  by  Walcott  [1884b,  PL  XI,  fig.  8] 
as  Lingula  ?  manticula. 


PLATE   XXI. 


75 


PLATE  XXI. 

f.  Flexure  line  of  area.  p.  Pedicle  groove. 
c.  ITmbonal  muscle  scar.  s.  Median  septum, 

h.  Central  muscle  scar.  v.  Visceral  cavity. 

j.  Anterior  lateral  muscle  scar.  vs.  Main  va.scular  sinus. 

LiNGULELLA    PERATTENUATA    (Whitfield)    (p.  523). 

Figure  1.  Cast  of  the  interior  of  a  ventral  valve  from  Locality  355,  Middle  (anibriaii  .sandstones  on  Red  Canyon  Creek, 

Black  Hills,  South  Dakota.     U.  S.  Nat.  Mus.  Cat.  No.  27423a. 
la.  Cast  of  the  interior  of  a  ventral  valve  from  Locality  74,  Middle  Cambrian  sandstone,  head  of  Nunkowf  ap 

Valley,  Grand  Canyon  of  the  Colorado,  Arizona.     U.  S.  Nat.  Mus.  Cat.  No.  51796a. 
lb.  Narrow,  partly  exfoliated  ventral  valve,  with  the  apex  rounded,  from  Locality  355,  Middle  Cambrian 

sandstones  on  Red  Canyon  Creek,  Black  Hills,  South  Dakota.     U.  S.  Nat.  Mus.  Cat.  No.  24589a. 

Type  specimen,  figured  by  Whitfield  [1880,  PI.  II,  fig.  9]  as  Lingulepis  peratlenuatiis. 
Ic.  Cast  of  the  interior  of  a  ventral  valve  associated  with  the  valve  represented  by  figure  1.     U.  S.  Nat.  Mus. 

Cat.  No.  27423b.     This  specimen  occurs  on  the  same  hand  specimen  with  figured  specimens  of  Lin- 

gulella  (Lingulepis)  acuminata. 
Id.  Cast  of  the  interior  of  a  dorsal  valve  associated  with  the  valves  represented  by  figures  1  and  Ic.     U.  S.  Nat. 

Mus.  Cat.  No.  27423c. 
le.  Cast  of  the  interior  of  a  ventral  valve  from  Locality  67c,  Upper  Cambrian  sandstone,  Tatur  Hill,  Burnet 

County,  Texas.     U.  S.  Nat.  Mus.  Cat.  No.  27424a. 
If.  Partly  exfoliated  dorsal  valve  from  Locality  68y,  Upper  Cambrian  .sandstone,  Packsaddle  Mountain,  Llano 

County,  Texas.     U.  S.  Nat.  Mus.  Cat.  No.  27422a. 
Ig.  Partly  exfoliated  dorsal  valve  a-ssociated  with  the  valve  represented  by  figure  If.     U.  S.  Nat.  Mus.  Cat. 

No.  27422b. 
Ih.  Cast  of  the  interior  of  a  dorsal  valve  associated  on  the  same  hand  specimen  with  the  valve  represented  by 

figure  lb.     U.  S.  Nat.  Mus.  Cat.  No.  24589b.     Specimen  figured  by  Whitfield  [1880,  PI.  II,  fig.  8]  a.s 

Lingulepis  perattenuatus. 
li.  Cast  of  the  interior  of  a  dorsal  valve  associated  with  the  valves  represented  by  figiu-es  lb  and  Ih.     U.  S.  Nat. 

Mus.  Cat.  No.  24.589c.     Specimen  figured  by  Whitfield  [1880,  PI.  II,  fig.  7]  as  Lingulepis  perattenuatus. 

LiNGXJLELLA    SIMILIS    (Walcott)     (p.  532). 

FIGURE  2.  Cast  of  the  interior  of  a  ventral  valve,  the  type  specimen,  from  Locality  88a,  Middle  Cambrian  limestone, 
near  Dcadwood,  Black  Hills,  South  Dakota.     U.  S.  Nat.  Mus.  Cat.  No.  27.339a. 

2a.  Cast  of  the  interior  of  a  dorsal  valve  a.ssociated  with  the  specimen  represented  by  figure  2.  U.S.  Nat.  Mus. 
Cat.  No.  27339b. 

2b  and  2c.  Partly  exfoliated  ventral  and  dorsal  valves,  respectively,  associated  with  the  specimens  repre- 
sented by  figures  2  and  2a.     IT.  S.  Nat.  Mus.  Cat.  Nos.  27339c  and  27339d,  respectively. 

2d.  Small,  strongly  convex  dorsal?  valve  doubtfully  referred  to  this  species,  from  same  locality  and  bed  of 
limestone  as  the  specimens  represented  by  figures  2,  2a-c.     U.  S.  Nat.  Mus.  Cat.  No.  27339e. 

2e.  Cast  of  the  interior  of  an  unusually  convex,  elongate  ventral  valve.     U.  S.  Nat.  Mus.  Cat.  No.  27340a. 

2f.  Cast  of  the  interior  of  a  ventral  valve  that  narrovTs  toward  the  frontal  margin.  U.  S.  Nat.  Mus.  Cat.  No. 
27340b. 

2g  and  2h.  Casts  of  two  dorsal  valves  that  show  variation  in  outline.  U.  S.  Nat.  Mus.  Cat.  Xo.s.  27340c  and 
27340d,  respectively. 

2i  and  2j.  Casts  of  associated  ventral  and  dorsal  valves  that  approach  most  closely  the  typical  forms  from  the 
Black  Hills.     U.  S.  Nat.  Mus.  Cat.  Nos.  27340e  and  27340f,  respectively. 

The  specimens  from  which  figures  2e  to  2j  are  drawn  are  all  from  Locality  97a,  I "pper  Cambrian  sandstone,  at  ^^'in- 
field,  Wisconsin. 

Figures  3  and  3a.  Casts  of  the  interior  of  ventral  valves  from  Locality  106,  .Middle  Cambrian  .shaly  s;indstones  of  the 
Rome  formation,  in  Bays  Mountains,  10  miles  (16.1  km.)  southeast  of  Knoxville,  Tennessee.    U.  S.  Nat. 
Mus.  Cat.  Nos.  27367a  and  27367b,  respectively. 
3b.  Cast  of  the  interior  of  a  ventral  valve  from  Locality  10a,  Middle  Cambrian,  at  the  same  general  locality  as 

the  specimens  represented  by  figures  3  and  3a.     U.  S.  Nat.  Mus.  Cat.  No.  27326a. 
3c  and  3d.  Casts  of  the  int;  rior  of  dorsal  valves  associated  with  the  ventral  valves  represented  by  figures  3  and 
3a.     U.  S.  Nat.  Mus.  Cat.  Nos.  27367c  and  27367d,  respectively. 
76 


U.  S.   GEOLOGICAL  SURVEY 


MONOGRAPH   LI     PL.  XXI 


vy 


^1 

V 

''/j'-t-J  «s.^^V» 

y^^Vt^ 

4a 

hNCES 

WIESER  DEL. 

HCklOTVPC    CO    BOSTON. 


PLATE  XXI.  77 

LiNGULELLA   (LiNGULEPIS)  ROWEI    (Walcott)    (p.  558). 

Figure  4.  Exfoliated  ventral  valve,  the  type  specimen.     U.  S.  Nat.  Mus.  Cat.  No.  51897a. 
4a.  Exfoliated  dorsal  valve.     U.  S.  Nat.  Mius.  Cat.  No.  51897b. 
4b.  Enlargement  of  the  outer  surface  of  another  specimen.     U.  S.  Nat.  Mus.  Cat.  No.  51897c, 

The  three  specimens  from  which  figures  4,  4a-b  are  drawn  are  from  Locality  14p,  Lower  Cambrian  limestone  near 
Resting  Springs,  Inyo  County,  California. 

LiNGULELLA    RANDOMENSIS    (Walcott)    (p.  530). 

Figure  5.  Ventral  valve,  the  type  specimen,  showing  the  cast  of  the  area  and  pedicle  groove.     U.  S.  Nat.  Mus.  Cat. 
No.  35208a. 
5a.  Dorsal  valve  associated  with  specimen  represented  by  figure  5.     U.  S.  Nat.  Mus.  Cat,  No.  35208b, 

The  specimens  represented  are  both  from  Locality  6y,  Upper  Cambrian,  on  the  north  side  of  Random  Island,  be- 
tween Birch  and  Sandy  points.  Smith  Sound,  Trinity  Bay,  Newfoundland, 

LiNGULELLA    SCHUCHERTI    (Walcott)    (p.  530). 

Figure  6.  Cast  of  a  ventral  valve,  the  type  specimen,  showing  the  area  and  pedicle  furrow,  from  Locality  367,  Low^r 
Cambrian  limestone,  Troy,  Rensselaer  County,  New  York,     U,  S,  Nat,  Mus,  Cat,  No,  51775a, 


PLATE    XXII. 


79 


PLATE  XXII. 


a.  Central  lateral  space  of  area, 
a'.  Outer  lateral  space  of  area, 
c.  Trapezoidal  area,  including  central,  middle 

lateral,  and  outside  lateral  inascle  scars. 
f.  Flexure  line  of  area, 
h.  Central  muscle  scar. 


i.  Transmedian  mu-scle  scar. 

j.  .\nterior  lateral  rnascle  scar, 
ps.  Parietal  band. 

V.  Visceral  cavity. 
vs.  Main  vascular  sinas. 

X.  Heart-shaped  cavity. 


LiNGULELLA    GRANVILLEN.SI.S    Walcott    (p.  504). 

Figure  1.  Exterior  of  partly  exfoliated  ventral  valve  from  Locality  38a,  Lower  Cambrian  limestone,  2  miles  south  of 
North  Granville,  Washington  County,  New  York.  U.  S.  Nat.  Mus.  Cat.  No.  17440a.  Type  speci- 
men, figured  by  Walcott  [1887,  PI.  I,  fig.  15b;  and  1891a,  PI.  LXVII,  fig.  4b].  The  specimen 
figured  by  Walcott  [1887,  PI.  I,  fig.  15c;  and  lS91a,  PI.  LXVII,  fig.  4c]  is  not  refigured  in  this  mono- 
graph.    It  is  in  the  collections  of  the  I'nited  States  National  Museum,  Catalogue  No.  17440e. 

la.  Exterior  of  partly  exfoliated  ventral  valve  associated  with  the  valve  represented  by  figure  1.  U.  S. 
Nat.  Mus.  Cat.  No.  17440b. 

lb.  Interior  of  a  small  ventral  valve  from  Locality  37b,  Lower  Cambrian,  one-fourth  mile  ea.-<t  of  Salem,  Wash- 
ington County,  New  York,  showing  the  visceral  cavity  and  main  vascular  sinuses.  U.  S.  Nat.  Mus. 
Cat.  No.  52036a. 

Ic.  Exterior  of  a  partly  exfoliated  dorsal  valve  associated  with  the  valve  represented  by  figure.-)  1  and  la. 
U.  S.  Nat.  Mus.  Cat.  No.  17440c.  Specimen  figured  by  Walcott  [1887,  PI.  I,  fig.  15;  and  1891a,  PI. 
LXVII,  fig.  4]. 

Id.  Cast  of  the  interior  of  a  dorsal  valve  associated  with  the  valves  represented  by  figures  1,  la,  and  Ic,  showing 
the  visceral  area  with  its  muscle  scars,  and  an  unusually  complex  system  of  vascular  canals.  U.  S. 
Nat.  Mus.  Cat.  No.  17440d.  Specimen  figured  by  Walcott  [1887,  PI.  I,  fig.  1.5a:  and  18^a,  PI. 
LXVII,  fig.  4a]. 

Obolus  lamborni  (Meek)  (p.  393). 

Figure  2.  Interior  of  a  flattened  ventral  valve  from  Locality  llj.  Middle  Cambrian  shale  at  Mine  Lamotte,  Madison 

County,  Missouri.     V.  S.  Nat.  Mus.  Cat.  No.  51553a. 
2a.  Cast  of  the  interior  of  a  ventral  valve  associated  with  the  valve  represented  by  figure  2.     L"^.  S.  Nat.  Mus. 

Cat.  No.  51553b. 
2b.  Very  fine  cast  of  the  interior  of  a  ventral  valve  from  Locality  121,  Middle  Cambrian  Rogersville  shale,  road 

just  east  of  Harlan  Knob,  4  miles  northeast  of   Rogersville,  Hawkins   County,  Tennessee.     U.  S. 

Nat.  Mus.  Cat.  No.  51558a. 
2c.  Cast  of  the  interior  of  a  ventral  valve  associated  with  the  specimen  represented  by  figure  2b,  which  has 

very  much  the  same  appearance  as  the  specimen  represented  by  figure  2a  from  the  shale  in  Missouri. 

U.  S.  Nat.  Mus.  Cat.  No.  51558b. 
2d.  Cast  of  the  outer  surface  of  a  ventral  valve  associated  with  the  valves  represented  by  figures  2b  and  2c, 

showing  the  strong  concentric  stride  and  fine  radiating  striie.     V.  S.  Nat.  Mus.  Cat.  No.  515.58c. 
2e  and  2f.  Casts  of  the  interior  of  compressed  ventral  valves  associated  with  those  represented  by  figures 

2b-d,  illustrating  variation  in  form,  figure  2f  being  the  result  of    distortion.    -U.  S.  Nat.  Mus.  Cat. 

Nos.  51558d  and  51558e,  respectively. 
2g  and  2h.  Very  fine  interior  casts  of  dorsal  valves  associated  with  the  ventral  valves  illustrated  by  figures 

2b-f.     The  variation  in  the  character  of  the  inner  surface  is  well  illustrated  by  the.'»e  two  figures;  in 

figure  2h  there  are  only  faint  indications  of  papilke,  while  in  figure  2g  they  are  abundant.     U.  S. 

Nat.  Mus.  Cat.  Nos.  51558f  and  51558g,  respectively.     The  area  of  figure  2h  is  represented  in  figure  2m. 
2i  and  2j.  Casts  of  the  interior  of  two  dorsal  valves  associated  with  the  two  ventral  valves  represented  by 

figures  2  and  2a,  at  Locality  llj,  near  Mine  Lamotte,  Missouri.    U.  S.  Nat.  Mus.  Cat.  Nos.  51553c 

and  51553d,  respectively.     Figure  2j  represents  the  type  specimen. 
2k.  Cast  of  a  dorsal  valve  associated  with  the  valves  represented  by  figures  2b-h  (Locality  121 1,  tliat  illustrates 

variation  in  form.     U.  S.  Nat.  Mus.  Cat.  No.  51558h. 
21.  Cast  of  largo  dorsal  valve  from  Locality  124a,  Middle  Cambrian  shales  on  Big  Creek,  southeast  of  Harlan 

Knob,  4  miles  northeast  of  Rogersville,  Hawkins  County,  Tennessee.     I'.  S.  Nat.  Mus.  Cat.  No. 

51557a. 
2m.  Enlargement  and  partial  restoration  of  the  area  of  the  dorsal  valve  represented  by  figure  2h.     I'.  S.  Nat. 

Mus.  Cat.  No.  51558g. 
2n.  Cast  of  a  dorsal  valve  associated  with  the  valves  represented  by  figures  2b-h.     U.  S.  Nat.  Mus.  Cat.  No. 

51.558i. 
80 


U.  S.   GEOLOGICAL  SURVEY 


MONOGRAPH   LI     PL.  XXII 


2" 


FRANCES  WIESER  DEL. 


.iELlOTVPC   CO   BOSTrtll 


PLATE    XXIII. 


62667°— VOL  51,  pt  2—12 6  81 


PLATE  XXIII. 


a.  Central  lateral  space  at  area, 
a'.  Outer  lat<!ral  space  of  area. 
f.  Flexure  lines  of  area, 
h.  Central  muscle  scar, 
i.  Transinedian  muscle  scar. 


j.  Anterior  lateral  muscle  scar, 
p.  Pedicle  ktoovc. 
s.  Median  septum. 
V.  Visceral  cavity, 
vs.  Main  vascular  sinus. 


Obolus  willisi  (Walcott)  (p.  420). 

Figure  1.  Cast  of  a  ventral  valve,  the  type  specimen,  compressed  in  shale,  Locality  140a,  .Mi<lille  CamVjrian,  near 

Cave  Spring,  Floyd  County,  Georgia.     U.  S.  Nat.  Mus.  Cat.  No.  27.345a. 
la.  Cast  of  a  ventral  valve  compressed  in  shale,  Locality  107b,  Middle  Cambrian,  near  Copiier  Ridge,  11  miles 

northwest  pf  Knoxville,  Tennessee.     U.  S.  Nat.  Mus.  Cat.  No.  27343a. 
lb.  Cast  of  a  ventral  valve  compressed  in  shale,  that  shows  the  pitted  or  punctate  character  of  the  interior  of  the 

shell.     Same  locality  as  specimen  represented  by  figure  la.     U.  S.  Nat.  Mus.  Cat.  No.  27343b. 
Ic.  Cast  of  the  outer  surface  of  a  ventral  valve,  from  same  band  of  shale  as  specimen  represented  by  figure  la. 

U.  S.  Nat.  Mus.  Cat.  No.  27343c. 
Id.  Cast  of  the  outer  surface  of  a  dorsal  valve  associated  with  specimen  represented  by  figure  la.     U.  S.  Nat. 

Mus.  Cat.  No.  27343d. 
le.  Cast  of  a  ventral  valve  distorted  by  compression  in  the  same  band  of  shale  as  the  specimen  represented  by 

figure  la.     U.  S.  Nat.  Mus.  Cat.  No.  27343e. 
If.  Cast  showing  part  of  a  ventral  valve,  the  outline  of  which  is  restored  from  associated  specimens.     It  occurs 

in  the  calcareous  sandstone  embedded  in  the  shales  of  Locality  107b,  Middle  Cambrian,  near  Copper 

Ridge,  11  miles  northwest  of  Knoxville,  Tennessee.    U.  S.  Nat.  Mus.  Cat.  No.  27343f. 
Ig.  Cast  of  the  interior  of  a  dorsal  valve  associated  with  the  specimen  represented  by  figure  If.     V.  S.  Nat. 

Mus.  Cat.  No.  27343g. 
Ih.  Cast  of  the  interior  of  a  dorsal  valve  a.ssociated  with  specimen  represented  by  figure  If  but  which  is  more 

transverse.     U.  S.  Nat.  Mus.  Cat.  No.  27343h. 
li.  Distorted  cast  of  a  ventral  valve  from  Locality  101b,  Middle  Cambrian  shale  3.5  miles  southwest  of  Rogers- 

ville,  Tennessee.    U.  S.  Nat.  Mus.  Cat.  No.  27344a. 
Ij.  Flattened  ventral  valve,  showing  the  strong  interrupted  radiating  lines  and  the  strong  concentric  rugose 

lines  of  growth.     Locality  93,  Upper  Cambrian  shale,  near  Jordans  on  (.'owan  Creek,  Cherokee  County, 

Alabama.     IT.  S.  Nat.  Mus.  Cat.  No.  27346a. 

LiNGULELLA    TAEPA  (Walcott)   (p.  584). 

Figure  2.  Exfoliated  ventral  valve  from  sandy  shales,  which  shows  general  outline  and  some  of  the  markings  of  the 

interior  of  the  shell.     U.  S.  Nat.  Mus.  Cat.  No.  27342a. 
2a.  Compressed,  slightly  distorted  ventral  valve,  the  type  specimen,  from  argillaceous  shales  interbedded 

with  the  sandy  shales  in  which  "the  specimen  represented  by  figure  2  occurs.     V.  S.  Nat.  Mus.  Cat. 

No.  27342b. 
2b.  Cast  of  a  dorsal  valve,  from  calcareous  layers  in  the  sandy  shale  in  which  specimen  represented  by  figure  2 

occurs.     U.  S.  Nat.  Mus.  Cat.  No.  27342c. 
2c.  Somewhat  more  elongate  shell  than  that  represented  by  figure  2b,  with  which  it  is  associated,  and  which 

is  somewhat  doubtfully  identified  as  a  dorsal  valve.     U.  S.  Nat.  Mus.  Cat.  No.  27342d. 

The  specimens  represented  are  all  from  Locality  11,  Middle  Cambrian,  1  mile  east  of  Post  Oak  Springs,  Roane 
County,  Tennessee. 

Obolus  mcconnelli  (Walcott)  (p.  .396). 

Figure  3.  Interior  of  a  crushed  and  broken  ventral  valve,  the  type  specimen,  from  Locality  14s,  Middle  Cambrian 
Ogygopsis  zone  on  Mount  Stephen,  British  Columbia.    U.  S.  Nat.  Mus.  Cat.  No.  51572a. 
3a.  Interior  of  an  associated  fragmentary  ventral  valve  of  the  broad  form.     U.  S.  Nat.  Mus.  Cat.  No.  51572b. 
Copied  from  Walcott  [1908c,  PI.  I,  fig.  2].     (See  note  under  fig.  3d,  below.) 

Obolus  mcconnelli  pelias  (Walcott)  (p.  398). 

(PI.  XXXIX,  figs.  5,  5a-c.l 

Figure  3b.  Interior  of  a  broad  form  of  dor,«al  valve,  the  type  specimen,  from  Locality  llq,  Mi(l<lle  Cambrian  Marjuni 
limestone,  ridge  east  of  Wheeler  Amphitheater,  House  Range,  L'tah.     U.  S.  Nat.  Mus.  Cat.  No.  51592a. 
3c.  Interior  of  an  associated  dorsal  valve.     U.  S.  Nat.  Mus.  Cat.  No.  51592b. 
82 


U.  S.   GEOLOGICAL  SURVEY 


MONOGRAPH   Lt     PL.  XXIII 


FRANCES  WIESER  DEL. 


MELIOTTPE   CO   BOSTOM 


PLATE  XXIII.  83 

Obolus  septalis  (Walcott)  (p.  414). 

[PI.  XXXIV,  n«.s.  2,  2a.l 

Figure  3d.  Dorsal  valve  from  Locality  14s,  Middle  Cambrian  Ogygopsis  zone  on  Mount  Stephen,  British  Columbia. 
U.  S.  Nat.  Mus.  Cat.  No.  24069a.  Copied  from  Walcott  [lOOSc,  V\.  I,  fit;.  2a],  where  it  was  figured 
as  Obolus  mcconnelli. 

Obolus  mcconnelli  decipiens  Walcott  (p.  398). 

Figure  4.  Compressed  ventral  valve,  the  type  specimen,  from  Locality  7v,  Upper  Cambrian  shales  4.25  miles  south- 
southeast  of  Emigrant  Peak,  Esmeralda  County,  Nevada.     U.  S.  Nat.  Mus.  Cat.  No.  51.586a. 

4a.  Compressed  ventral  valve  from  Locality  8m,  Middle  Cambrian  limestone  4  miles  northeast  of  Osceola, 
White  Pine  County,  Nevada.     U.  S.  Nat.  Mus.  Cat.  No.  51585a. 

4b.  Ventral  valve  associated  with  specimen  represented  by  figure  4a.     U.  S.  Nat.  Mus.  Cat.  No.  51585b. 

Obolus  fragilis  (Walcott)  (p.  392). 

Figure  5.  Cast  of  the  interior  of  a  ventral  valve,  the  type  specimen,  from  Locality  1,  Middle  Cambrian  shales  on 

Manuels  Brook,  Conception  Bay,  Newfoundland.     U.  S.  Nat.  Mus.  Cat.  No.  27317a. 
5a.  Dorsal  valve  associated  with  the  specimen  represented  by  figure  2.     U.  S.  Nat.  Mus.  Cat.  No.  27317b. 
5b.  Outline  of  the  dorsal  valve,  showing  area,  from  Locality  2,  Middle  ('ambrian  .shale  from  a  higher  horizon 

than  that  represented  by  figure  5,  on  Manuels  Brook,  Conception  Bay,  Newfoundland.     U.  S.  Nat. 

Mus.  Cat.  No.  569na. 
5c.  Cast  of  the  interior  of  a  dorsal  valve  associated  with  the  specimen  represented  by  figure  5.     U.  S.  Nat. 

Mus.  Cat.  No.  27317c. 
5d.  Cast  of  the  interior  of  a  dorsal  valve,  showing  concentric  and  radiating  stri*,  as.sociated  with  specimen 

represented  by  figure  5b.     U.  S.  Nat.  Mus.  Cat.  No.  56911b. 
5e.  Broad  dorsal  valve  associated  with  specimen  represented  by  figure  5.     U.  S.  Nat.  Mus.  Cat.  No.  27317d. 


PLATE    XXIV. 


85 


PLATE  XXIV. 

a.  Central  lateral  space  of  area.  p.  Pedicle  groove, 

a'.  Outer  lateral  space  of  area. ,  s.  Median  septum, 

f.  Flexure  line  of  area.  v.  \Tsceral  cavity, 

h.  Central  muscle  scar.  vs.  Main  vascular  sinus, 
j.  Anterior  lateral  muscle  scar. 

LiNGULELLA    NANNO   (Willcott)    (p.  521). 

Figures  1  and  la.  Ventral  valves,  preserving  natural  form  and  convexity,  from  Locality  16,  Middle  Cambrian 
limestones  in  Blountsville  Valley,  Blount  County,  Alabama.     U.  S.  Nat.  Mus.  Cat.  Nos.  27328a  and 
27328b,  respectively.    Figure  la  represents  the  type  specimen, 
lb  and  Ic.  Dorsal  valves  associated  with  the  specimens  represented  by  figures  1  and  la.     U.  S.  Nat.  Mus. 

Cat.  Nos.  27328c  and  27328d,  respectively. 
Id.  Unusually  large  and  convex  dorsal  valve  from  Locality  91,  Middle  Cambrian  limestone  at  Cedar 
Bluff,  Cherokee  County,  Alabama.     U.  S.  Nat.  Mus.  Cat.  No.  57005a. 

LiNGULELLA    LEGS    (WalcOtt)     (p.  513). 

Figure  2.  Partly  exfoliated  ventral  valve.     U.  S.  Nat.  Mus.  Cat.  No.  27323a. 

2a.  Cast  of  the  interior  of  a  ventral  valve,  the  type  specimen.     U.  S.  Nat.  Mus.  Cat.  No.  27323b. 
2b  and  2c.  Casts  of  interior  of  two  dorsal  valves.    2c  is  strongly  convex  and  unusually  narrow  and  elongate. 
T'.  S.  Nat.  Mus.  Cat.  Nos.  27323c  and  27323d,  respectively. 

The  specimens  represented  are  all  from  Locality  96,  Upper  Cambrian  limestone,  1.5  miles  south  of  Rome,  Floyd 
County,  Georgia. 

LiNGULELLA    HELENA    (Walcott)     (p.  506). 

Figure  3.  Exterior  of  a  slightly  distorted  ventral  valve  from  Locality  302s,  Middle  Cambrian  siliceous  shale  1.5  miles 

south  of  Helena,  Lewis  and  Clark  County,  Montana.     U.  S.  Nat.  Mus.  Cat.  No.  27320a. 
3a  and  3b.  Casts  in  siliceous  shale  of  the  interior  of  two  ventral  valves  that  differ  in  outline,  from  the  locality 

represented  by  figure  3.     V.  S.  Nat.  Mus.  Cat.  Nos.  27320b  and  27320c,  respectively.     Figure  3a 

represents  the  type  specimen. 
3c.  Cast  of  the  interior  of  a.dorsal  valve  showing  area,  from  the  locality  represented  by  figure  3.     U.  S.  Nat. 

Mus.  Cat.  No.  27320d. 
3d.  Small  ventral   valve  doubtfully  referred   to  the  species,  from  Locality  30a,  Middle  Cambrian  shale  in 

Big  Cottonwood  Canyon,  near  Salt  Lake  City,  Utah.     U.  S.  Nat.  Mus.  Cat.  No.  51819a. 

LiNGULELLA    DUBIA    (Walcott)     (p.  494). 

Figure  4.  Cast  of  interior  of  ventral  valve,  the  type  specimen,  associated  with  Obolus  (Westonia)  ella  at  Locality  31, 
Middle  Cambrian  shales  at  Pioche,  Nevada.     V.  S.  Nat.  Mus.  Cat.  No.  27314a. 
4a.  Cast  of  interior  of  dorsal  valve  on  same  piece  of  shale  with  the  specimen  represented  by  figure  4.     U.  S. 
Nat.  Mus.  Cat.  No.  27314b. 

LiNGULELLA    ARGITA    (Walcott)     (p.  478). 

Figure  5.  Perfect  ventral  valve,  the  type,  from  Lmality  3131,  Upper  Cambrian  limestone  at  Schellbourne,  Schell 
Creek  Range,  Nevada.     U.  S.  Nat.  Mu.-s.  Cat.  No.  27305a.     DrawTi  from  specimen  represented  by 
White  [1877,  PI.  Ill,  fig.  2a]  as  LinguUi  f  maiiliada. 
5a.  Dorsal  valve  that   is  doubtfully  referred  Ifi  this  species  from  Locality  313a,  Mi<ldle  Cambrian  limestone 

at  Schellbourne,  Nevada.     U.  S.  Nat.  Mus.  Cat.  No.  51845a. 
5b.  Partly  exfoliated  dorsal  valve  from  Locality  lOy,  Middle  Cambrian  Marjum  iimeatone,  near  Marjum 
Paas,  House  Range,  Utah.     U.  S.  Nat.  Mus.  Cat.  No.  58303. 
86 


U.   S.  GEOLOGICAL  SURVEY 


MONOGRAPH   LI     PL.  XXIV 


FRANCES  VvieSER  DEL. 


LiOTvpe  CO  eosTOH 


PLATE  XXIV.  87 

LiNGULELLA    AUGA    (Walcott)     (p.  480). 

FiouREs  6  and  6a.  Casts  in  shaly  limcstune  (if  interior  of  two  ventral  valves.     U.  S.  Nat.  Mu.s.  Cat.  Nos.  27306a  and 

27306b,  respectively. 
6b.  Cast  of  the  posterior  portion  of  the  interior  of  a  distorted  ventral  valve,  the  type  specimeri.     U.  S.  Nat. 

Mus.  Cat.  No.  27306c. 
6c.  Cast  of  the  posterior  portion  of  the  interior  of  a  ventral  valve,  showing  a  trace  of  the  vi.sceral  area.     U.  S. 

Nat.  Mus.  Cat.  No.  27306d. 
6d  and  6e.  Casts  of   the  interior  of  two  dorsal  valves.     U.  S.  Nat.  Mus.  Cat.  Nos.  27306e  and  27306f 

respectively. 

The  specimens  illustrated  by  figures  6,  6a-e  are  from  Locality  10a,  Middle  Cambrian  shaly  sandstones  at  Shooka 
Gap,  10  miles  southeast  of  Knoxville,  Tennessee. 

Figures  6f  and  6g.  Ventral  and  dorsal  valves  from  Locality  10b,  a  siliceous  limestone  interbedded  in  the  Middle 
Cambrian  shaly  sandstones  at  Shocks  Gap,  10  miles  southeast  of  Knoxville,  Tennessee.  The  outer 
surface  with  strong  concentric  stria?  is  finely  preserved.  U.  S.  Nat.  Mus.  Cat.  Nos.  27306g  and  27306h, 
respectively, 

LiNGULELLA  TUMiDA  Mattliew   (p.  537). 

Figure  7.  Exterior  of  ventral  valve  from  Locality  13i,  Middle  Cambrian  sandy  shales  on  Ciillis  Brook,  Cape  Breton, 

Nova  Scotia.     U.  S.  Nat.  Mus.  Cat.  No.  51769a. 
7a.  Cast  of  the  interior  of  a  ventral  valve  associated  with  the  shell  represented  by  figure  7,  showing  the  high 

area  and  strong  vascular  sinuses.     U.  S.  Nat.  Mus.  Cat.  No.  51769b. 
7b.  Cast  of  the  interior  of  a  ventral  valve  from  Locality  13r,  a  little  different  horizon  from  that  represented 

by  Locality  131,  Middle  Cambrian  sandy  shales  on  Gillis  Brook,  Cape  Breton,  Nova  Scotia.     U.  S. 

Nat.  Mus.  Cat.  No.  57011a. 
7c.  Exterior  of  ventral  valve  a,ssociatcd  with  the  shell  represented  by  figure  7.     U.  S.  Nat.  Mus.  Cat.  No. 

51769c. 
7d.  Cast  of  the  interior  of  a  ventral  valve  associated  with  the  shell  represented  by  figure  7b,  retaining  a 

portion  of  the  shell  on  the  umbo.     U.  S.  Nat.  Mus.  Cat.  No.  57011b. 


PLATE   XXV. 


89 


PLATE  XXV. 

a.  Central  lateral  space  of  are<i.  p.  Pedicle  ktootc. 

a'.  Outer  lateral  space  of  area.  ps.  Parietal  l)aad. 
f.  Flexure  line  of  area.  s.  Median  septum, 

h.  Central  muscle  scar.  v.  Visceral  cavity, 

i.  Transmedian  mu.scle  scar.  vs.  Main  vascular  sinus, 
j.  .\nterior  lateral  muscle  scar. 

LiXGULELLA    IIAYESI    (Walcott)    (p.  505). 

Figure  1.  Cast  of  the  interior  of  a  ventral  valve,  showing  the  area  and  portions  of  the  visceral  cavity.     I'.  S.  Xat. 

Mus.  Cat.  No.  27319] . 
la.  Interior  of  a  partly  weathered  ventral  valve.     U.  S.  Nat.  Mus.  Cat.  No.  27319a. 
lb  and  Ic.  Casts  of  the  interior  of  the  ventral  valve,  showing  the  position  of  the  main  vascular  sinuses,  the 

visceral  cavity,  and  the  area.     U.  S.  Nat.  Mus.  Cat.  Nos.  27310b  and  27319c,  respectively.     Figure 

lb  represents  the  type  specimen. 
Id.  Enlargement  of  the  cast  of  the  area  i>f  the  ventral  valve,  showing  the  pedicle  groove,  the  flexure  line,  and 

the  central  and  outer  lateral  spaces  of  the  area.     U.  S.  Nat.  Mus.  Cat.  No.  27319d. 
le.  Cast  of  the  interior  of  a  dorsal  valve  showing  the  position  of  the  central  (h)  and  anterior  lateral  (j)  muscle 

scars,  the  scar  of  the  parietal  band  (ps),  also  the  arching  forward  of  the  center  of  the  area.     U.  S.  Nat. 

Mus.  Cat.  No.  27319e. 
If,  Ig,  Ih,  and  li.  Casts  of  the  interior  of  dorsal  valves,  showing  variation  in  form  of  the  valve  and  in  the  posi- 
tion of  the  parietal  band  and  main  vascular  sinus.     The  latter  is  especially  well  shown  by  figure  Ig. 

U.  S.  Nat.  Mus.  Cat.  Nos.  27319f,  27319g,  27319h,  and  273191,  respectively. 
Ij.  Enlargement  of  the  area  of  the  dorsal  valve  represented  by  figure  If.     U.  S.  Nat.  Mus.  Cat.  No.  27319f. 

All  of  the  specimens  represented  occur  on  the  exterior  of  siliceous  nodules,  or  on  breaks  across  them,  from  Locality 
90x,  Middle  Cambrian  Conasauga  shale,  Coosa  Valley,  Cherokee  County,  Alabama. 

Obolus  (Westoxia)  chuarensis  (Wiilcott)   (p.  454). 

Figures  2  and  2a.  Partly  exfoliated  ventral  valves  from  Locality  73a,  Middle  Cambrian  sandstone,  Chuar  Valley, 

Grand  Canyon  of  the  Colorado,  Arizona,  showing  some  variation  in  form.     V.  S.  Nat.  Mus.  Cat.  Nos. 

57020a  and  57020b,  respectively.     Figure  2  represents  the  type  specimen. 
2b.  Crushed  ventral  valve  from  Locality  74b,  Middle  Cambrian  sandstone  in  Nunkoweap  Valley,  Grand 

Canyon  of  the  Colorado,  Arizona.     U.  S.  Nat.  Mus.  Cat.  No.  57021a. 
2c.  Exterior  of  a  rather  large  dorsal  valve  from  Locality  74,  Middle  Cambrian  sandstone  at  the  head  of  Nimko- 

weap  Valley,  Grand  Canyon  of  the  Colorado,  Arizona.     V.  S.  Nat.  Mus.  Cat,  No.  27310a. 
2d.  Cast  of  part  of  the  interior  of  a  dorsal  valve  associated  with  the  shells  represented  by  figures  2  and  2a, 

showing  a  median  depression  and  the  area.     V.  S.  Nat.  Mus.  Cat.  No.  57020r. 
2e.  Strongly  marked  cast  of  the  interior  of  a  dorsal  valve  associated  with  the  shell  represented  by  figure  2c, 

showing  the  depression  filled  by  the  ridges  adjacent  to  the  main  vascular  sinuses,  a  strong  central 

groove  corresponding  to  the  median  septum,  and  the  central  muscle  scars  (h).     U.  S.  Nat.  Mus. 

Cat.  No.  27310b. 

Obolu.s  zExrs  (Walcott)    (p.  4_'l). 

Figures  3,  3a,  and  3b.  Partly  exfoliated  ventral  valves,  showing  the  external  form  and  something  of  the  character 
of  the  different  layers  forming  the  shell.     V.  S.  Nat.  Mus.  Cat.  Nos.  27347a,  27347b,  and  27347c, 
respectively.     Figure  3a  represents  the  type  specimen. 
3c.  Partly  exfoliated  dorsal  valve.     V.  S.  Nat.  Mus.  Cat.  No.  27347d. 

The  specimens  represented  are  all  fmni  Locality  74,  Middle  Cambrian  sandstone,  near  the  head  of  Nunkoweap 
Valley,  Grand  Canyon  of  the  Colorado,  .Vrizona. 

Obolus  lamborni  minimus  (Walcott)  (p.  395). 

Figures  4  and  4a.  Casts  of  ventral  valves  that  were  comprc.«.sed  in  the  shale,     l'.  S.  Nat.  Mus.  Cat.  Nos.  27322a  and 
27322b,  respectively.     Figure  4  represents  the  type  specimen.  , 

4b.  Dorsal  valve  associated  with  the  ventral  valves  represented  by  figures  4  and  4a.     U.  S.  Nat.  Mus.  Cat. 
No.  27322c. 

The  specimens  illustrated  are  all  from  Locality  101a.  Middle  Cambrian  Rogersville  shale,  3.5  miles  southwest  of 
Rogersville,  Ilawkiivs  County,  Tennessee. 
90 


U.  S.   GEOLOGICAL  SURVEY 


MONOGRAPH   LI     PL.  XXV 


t) 


2b 


?" 


FRANCES  WIESER  DEL. 


cLiOTVPE  CO  e=si 


PLATE   XXVI. 


91 


PLATE  XXVI. 


c.  Trapezoidal  area,  including  central,  middle 
lateral,  and  outside  lateral  muscle  scars. 

f.  Fle.xure  line  of  area. 

g.  Umbonal  muscle  scar. 
h.  Central  muscle  scar. 

1.  Transmedian  muscle  scar. 


j.  Anterior  lateral  muscle  scar, 
m.  Pedicle  muscle, 
p.  Pedicle  groove, 
s.  Median  septum. 
V.  Visceral  cavity, 
vs.  Main  vascular  sinus. 


LiNGULELLA    PHAON    (Walcott)   (p.  525). 

Figure  1.  A'entral  valve  from  Locality  84a,  Upper  Cambrian  sandstone  at  River  Junction,  Houston  County,  Minne- 
sota, the  exterior  of  which  has  been  slightly  injured  by  abrasion.     U.  S.  Nat.  Mus.  Cat.  Xo.  27406a. 

la.  Dorsal  valve  associated  with  the  specimen  represented  by  figure  1.     U.  S.  Nat.  Mus.  Cat.  No.  27406b. 

lb.  Strongly  marked  cast  of  the  interior  of  a  ^•entral  valve  from  Locality  98x,  L^pper  Cambrian  sandstone  near 
Eau  Claire,  Wisconsin.  This  specimen  shows  the  broken  edge  of  the  undercut  that  extended  back 
under  the  area  and  the  deeply  impressed  character  of  t,he  channels  of  the  main  vascular  sinuses;  also 
the  large  size  of  the  pits  or  punctae  on  the  interior  of  the  .shell.     U.  S.  Xat.  Mus.  Cat.  Xo.  27331a. 

Ic.  Cast  of  the  interior  of  a  ventral  valve,  the  type  specimen,  associated  with  the  specimen  represented  by  fig- 
ure lb,  showing  more  definitely  the  interior  features  of  the  shell.  The  divided  umbonal  muscle  scars 
and  the  pedicle  muscle  scar  are  drawn  from  an  associated  ventral  valve.  The  central,  middle  lateral, 
and  outside  lateral  muscle  scars  are  not  differentiated  in  the  deeply  impressed  trapezoidal  area  (c); 
the  anterior  lateral  muscle  sears  (j)  are  well  shown.     U.  S.  Xat.  Mus.  Cat.  Xo.  27331b. 

Id.  Interior  cast  of  a  dorsal  valve  associated  with  the  specimen  represented  by  figure  lb,  having  the  same 
strongly  marked  characteristics  as  the  casts  of  the  ventral  valve.  The  cast  of  the  central  ridge  is  very 
pronounced,  and  it  is  ditHcult  to  say  just  where  the  central  muscle  scars  (h)  were  located.  They 
appear  to  be,  however,  as  indicated  on  the  ilra^ving,  which  brings  them  very  close  to  the  small 
anterior  lateral  scars.     U.  S.  Nat.  Mus.  Cat.  No.  27331c. 

le.  Interior  cast  of  a  very  strongly  marked  dorsal  valve  associated  with  the  specimen  represented  by  figure 
lb,  in  which  the  detailed  characters  are  lost.  The  general  effect  of  this  cast  is  much  like  that  of 
the  interior  cast  of  the  dorsal  valve  of  Lirigulella  grandis  (PL  XXXVIII,  fig.  2d).  U.  S.  Nat.  Mus. 
Cat.  Xo.  27331d. 

Obolus  sixoe  (Walcott)  (p.  415). 

Figure  2.  Interior  cast  of  a  veritral  valve.     U.  S.  Xat.  Mus.  Cat.  Xo.  27341a. 

2a.  Interior  of  a  ventral  valve  preserving  the  area  and  showing  the  undercut  beneath  the  area.  The  impres- 
sions of  the  visceral  cavity  are  indistinct.  U;  S.  Nat.  Mus.  Cat.  Xo.  27341b.  Another  specimen 
(Cat.  Xo.  27341c)  was  used  to  restore  parts  of  the  drawing. 

2b..  Cast  of  the  interior  of  a  ventral  valve,  showing  a  portion  of  the  shell  and  the  posterior  ])ortion  of  the  main 
vascular  sinuses.     L'.  S.  Nat.  Mus.  Cat.  Xo.  27341d. 

2c.  Dorsal  valve  from  which  the  exterior  layer  has  been  removed  so  as  to  .show  the  edges  of  the  oblique  interior 
lamellae.     U.  S.  Xat.  Mus.  Cat.  No.  27341e. 

2d.  Cast  showing  part  of  the  interior  of  a  ventral  valve.     U.  S.  Xat.  Mus.  Cat.  Xo.  27.341f. 

The  specimens  represented  by  figures  2,  2a-d  are  from  Locality  68y,  L'pper  Cambrian  reddish  brown  sandstone  on 
Packsaddle  Mountain,  Llano  County,  Texas. 

Figure  2e.  Cast  of  an  interior  of  a  ventral  valve.  The  strongly  marked  channel  of  the  parietal  scar  and  the  elevated 
ridge  in  front  of  it  is  very  characteristic  of  Obolus  apollinis  (PL  VII).  The  posterior  portion  toward 
the  area  is  restored  from  a  second  specimen.     U.  S.  Nat.  Mus.  Cat.  No.  51627a. 

2f.  Cast  showing  part  of  the  interior  of  a  dorsal  valve,  the  type  specimen.  The  anterior  lateral  .scars  are  well 
shown  on  another  specimen.     U.  S.  Nat.  Mus.  Cat.  X"o.  51627b. 

2g.  An  elongate  dorsal  valve  preserving  the  outer  surface  of  the  shell.     V.  S.  Nat.  Mus.  Cat.  No.  51627c. 

2h.  Enlai^ement  of  the  anterior  portion  of  a  .shell  to  illustrate  tlie  obli(|ue  lamcllie  forming  the  strong  shell. 
IT.  S.  Nat.  Mus.  Cat.  No.  5I627.1. 

The  specimens  represented  by  figures  2e-h  are  from  Locality  70,  L'pper  Cambrian  limestone  near  Morgans  Creek, 
Burnet  County,  Texas. 
92 


U.   S.   GEOLOGICAL  SURVEY 


MONOGRAPH   LI     PL.  XXVI 


FRANCES  WIESER  DEL. 


HELIOTyfe     CO    BOSTON 


PLATE  XXVI.  93 

LiNGULELLA    FKANKLINENSIS    (Walcott)   (p.  501). 

Figure  3.  Somewhat  crushed  ventral  valve,  the  type,  from  which  most  nf  the  shell  has  been  exfoliated.  Locality  87, 
Lower  Cambrian  limestone  near  Ilighgate  Falls,  Franklin  County,  Vermont.  U.  S.  Nat.  Mus.  Cat. 
No.  27318a. 

3a.  Dorsal  (?)  valve  from  the  locality  represented  by  figure  3,  preserving  the  outer  surface.  This  may  be.  how- 
ever, a  distorted  ventral  valve.     U.  S.  Nat.  Mus.  Cat.  No.  27318b. 

3b.  Largest  ventral  valve  in  the  collection.  Locality  28a,  Middle  ?  Cambrian,  near  Parker's  quarry,  Georgia, 
Vermont.     U.  S.  Nat.  Mus.  Cat.  No.  52454a. 

LiNGULELLA  INO   (Walcott)  (j).  507). 

Figure  4.  Cast  of  the  interior  of  a  ventral  valve,  the  type  specimen,  showing  somewhat  imperfectly  the  \-isceral 

cavity  and  main  vascular  sinuses.     U.  S.  Nat.  Mus.  Cat.  No.  27321a. 
4a.  Ventral  valve  preserving  a  portion  of  the  shell,  showing  the  area,  pedicle  groove,  and  flexure  lines  very' 

clearly.     U.  S.  Nat^  Mus.  Cat.  No.  27321b. 
4b.  Cast  of  the  interior  of  a  dorsal  valve,  showing  a  relatively  large  area  and  portions  of  the  shell  adhering  to  the 

cast.     U.  S.  Nat.  Mus.  Cat.  No.  27321c. 

The  specimens  represented  are  all  from  Locality  13b,  Middle  Cambrian  sandstones  northeast  of  Rhea  Springs, 
Roane  County,  Tennessee. 


PLATE    XXVII. 


95 


PLATE  XXVII. 

c.  Trapezoidal  area,  IncliKiinK  central,  middle  J.    \nterior  lateral  muscle  scar. 

lateral,  and  outside  lateral  muscle  scars.  m.  Pedicle  muscle. 

g.  Umlional  muscle  scar.  v.  Visceral  cavity, 

h.  Central  muscle  sear.  vs.  Main  vascular  sinus. 

LiNGULELLA  PRIMA  (Conrad  MS.)  (Hall)  (p.  526). 

FiGt'RE  1.  Cast  of  the  interior  of  a  ventral  valve,  .showing  the  pestle-shaped  ridge  that  filled  the  median  groove  of  the 
interior  of  the  shell.     U.  S.  Xat.  Mils.  Cat.  No.  27435a. 
la.  Exterior  of  a  ventral  valve,  showing  rather  strong  undulations  of  growth.     U.  S.  Xat.  Mus.  Cat.  No.  2743.5 
lb.  Fragment  of  a  ventral  valve,  showing  the  cast  of  the  area,  the  di\ided  umlicnial  muscle  scar  (g),  and  the 

pedicle  scar  (m).     U.  S.  Nat.  Mus.  Cat.  No.  27435c. 
Ic.  Partly  exfoliated  dorsal  valve.     U.  S.  Nat.  Mus.  Cat.  No.  27435(1. 

The  specimens  represented  are  all  from  Locality  77,  I'pper  Cambrian  sandstone,  Ausable  Chasm,  Essex  County, 
New  York. 

LiNGXJLELLA  IRIS  (Billings)  (p.  509). 

Figure  2.  Dorsal  valve,  the  type  specimen,  from  Locality  319d,  L'pper  Cambrian,  Point  Levis,  Quebec,  Canada. 
Geol.  Survey  Canada.  Redrawn  from  the  specimen  described  and  figured  by  Billings  [lS65a,  p.  301, 
fig.  290]  as  Lingula  iris. 

Obolus  prindlei  (Walcott)  (p.  409). 

Figure  3.  Ventral  valve,  the  type,  from  Locality  72a,  Lower  Cambrian.  1  mile  southwest  of  W'ynantskill,  Rensselaer 
County,  New  York,  showing  the  character  of  the  outer  surface  and  also  of  the  surface  of  the  inner 
layers  where  the  shell  Ls  exfoliated  over  its  umbonal  portion.     U.  S.  Nat.  Mus.  Cat.  No.  27333a. 

3a.  Cast  of  the  interior  of  a  ventral  valve  which  is  broken  away  a  little  at  the  beak.  This  specimen  Ls  associated 
on  the  same  hand  specimen  with  the  valve  represented  in  figure  3.     V.  S.  Nat.  Mus.  Cat.  No.  27333b. 

3b.  Portionof  a  ventral  valve  from  Locality  72a,  Lower  Cambrian,  1  mile  southwest  of  Wynantskill,  Rensselaer 
County,  New  York,  showing  the  cast  of  the  finely  punctate  inner  surface  and  the  peculiar  lamellose- 
like  striae  of  growth  upon  the  area.     U.  S.  Nat.  Mus.  Cat.  No.  27333c. 

3c.  Cast  of  the  interior  of  a  dorsal  valve,  associated  on  the  same  hand  specimen  with  the  \alve  represented  by 
figure  3,  showing  the  area.     U.  S.  Nat.  Mus.  Cat.  No.  27333d. 

3d.  Exterior  of  a  dorsal  valve  from  Locality  72,  Lower  Cambrian  limestone  5  miles  west  of  Albany,  ReiLsselaer 
County,  New  York,  illustrating  the  character  of  the  outer  surface.     U.  S.  Nat.  Mus.  Cat.  No.  27334a. 

3e.  Cast  of  the  interior  of  a  dorsal  valve  that  is  more  conve.x  and  more  oval  in  outline  than  the  specimen  repre- 
sented by  figure  3,  which  is  associated  on  the  same  hand  specimen  with  it.  U.  S.  Nat.  Mus.  Cat. 
No.  27333e. 

Obolus  ctane  (Billings)  (p.  3SS). 

Figure  4.  Cast  of  the  interior  oi  a  ventral  valve,  the  type  specimen,  which  preserves  a  portion  of  the  inner  layers 

of  the  shell  over  the  visceral  area. 
4a.  Imperfect  cast  of  a  ventral  valve,  showing  the  lamellated  shell  structure. 
4b.  Cast  of  the  interior  of  a  dorsal  valve.     The  muscle  scars  are  obscured  in  the  specimen  from  which  the  figure 

has  been  drawn,  and  those  that  appear  in  the  figure  are  from  another  specimen  occurring  in  the  same 

fragment  of  limestone. 

The  specimens  represented  are  all  from  Locality  314d,  Lower  Ordovician  limestone  4  miles  northeast  of  Portland 
Creek,  Newfoundland,  and  are  now  in  the  collections  of  the  Geological  Survey  of  Canada.  These  specimens  were 
illustrated  by  Billings  [18G5a,  figs.  20a-d,  p.  215],  but  further  identification  of  his  figures  with  those  in  this  monograph 
Ls  impossible. 

LiNGULELLA    lOLE   (Billillgs)    (p.  50S). 

Figures  Sand  5a.  Ventral  and  dorsal  valves,  respectively,  from  Locality  314d,  Lower  Ordovician  limestone  4  miles 
•     northeast  of  Portland  (reek,  Newfoundland.     Geol.  Survey  Canada.     Redrawn  from  the  two  speci- 
mens figured  by  Billings  [ISGoa,  figs.  199a-e,  p.  215]  as  Lingula  iolc.    The  ventral  may  be  taken  as 
the  type. 
96 


U.  S.   GEOLOGICAL  SURVEY 


MONOGRAPH    LI     PL.  XXVII 


3' 


3" 


•') 


FRANCES  WIE8ER  DEL. 


MCLioTvpE  cc  eo3roN 


PLATE  XXVII.  97 

LiNGTXLELLA  IRENE  (Billings)  (p.  50S). 

Figure  6.  Interior  of  a  flattened  ventral  valve,  preserving  the  area  and  portions  of  the  shell.     The  confenlric  striatum 
of  the  exterior  of  the  shell  is  shown  at  the  place  where  the  shell  is  broken  away. 
6a.  Partly  exfoliated  outer  surface  of  a  dorsal  valve  that  is  compressed  in  the  shale. 

The  specimens  represented  are  both  from  Locality  315a,  Lower  Ordovician  Levis  shale  at  Point  Levis,  Quebec, 
Canada,  and  are  in  the  collection  of  the  Geological  Survey  of  Canada.  They  were  described  and  fiirured  by  I'illings 
[18C2d,  pp.  71-72,  figs.  64a-b]  as  Lingula  irene.     Figure  6  may  be  take:i  as  the  type. 

LiNGTJLELLA   CUNEOLA    (Whitfield)    (p.  4SS). 

FiGiRE  7.  Cast  of  a  ventral  valve  from  Locality  355,  Middle  Cambrian  sandstone.  Red  Canyon  Creek,  Black  Hills, 

South  Dakota.     U.  S.  Nat.  Mas.  Cat.  No  24587a.    Type  specimen,  figured  by  Whitfield  [1S80,  PL  I, 

fig.  6]  as  Lingulepis  cuneolus.     The  specimen  figured  by  Whitfield  [1880,  PI.  I,  fig.  5]  is  not  figured  in 

this  monograph. 

7a.  Cast  of  the  interior  of  a  ventral  (?)  valve,  associated  with  the  valve  represented  by  figure  7,  preserving  a 

portion  of  the  shell  on  the  outer  margins.     V.  S.  Nat.  Mus.  Cat.  No.  33S73a. 
7b.  Cast  of  the  interior  of  a  dorsal  valve,  asseciated  with  specimens  represented  by  figures  7  and  7a.     V.  S. 
Nat.  Mus.  Cat.  No.  33873b. 
62667°— VOL  51,  pt  2—12 7 


PLATE   XXVIII. 


99 


PLATE  XXVIII. 

a.  Cfintral  lateral  space  of  area.  p.  Pedicle  groove. 
a'.  Outer  lateral  sjiace  of  area.  s.  Median-septum. 

f.  Flexure  line  of  area.  V.  Visceral  cavity. 

h.  Central  muscle  scar.  vs.  Main  vascular  sinus. 
i.  TranS7nedian  muscle  scar.  y.  See  text  (p.  478). 

j.  -Vnterior  lateral  muscle  scar. 

LiNGULELLA    AMPLA    (OwCIl)    (p.  477). 

Figure  1.  Ventral  valve  partly  broken  away  near  the  apex,  from  Locality  339e,  Middle  Cambrian  sandstone  on 
Mountain  Island,  Minnesota.  U.  S.  Nat.  Mus.  Cat.  No.  17S59b.  Type  specimen,  figured  by  Owen 
[1852,  PI.  IB,  fig.  5]  as  Lingula  ampla.  The  specimen  represented  by  figure  12  of  the  same  plate 
(Catalogue  No.  17859a)  is  not  figured  in  this  monograph. 

la.  Ventral  valve,  from  Locality  84s,  Middle  Cambrian  sandstone  near  Dakota,  Winona  County,  Minnesota. 
U.  S.  Nat.  Mus.  Cat.  No.  35241a. 

lb.  Dorsal  valve,  associated  with  specimen  represented  by  figure  la.     L'.  S.  Nat.  Mus.  Cat.  No.  35241b. 

Ic.  Cast  of  the  interior  of  a  ventral  valve  associated  with  the  specimen  represented  by  figure  la.  U.  S.  Nat. 
Mus.  Cat.  No.  35241c. 

Id.  Cast  of  the  interior  of  the  ventral  valve  represented  in  figure  If,  enlarged.  Locality  84s,  Middle  Cambrian 
sandstone  near  Dakota,  Winona  County,  Minnesota.     U.  S.  Nat.  Mus.  Cat.  No.  35241d. 

le.  Cast  of  the  interior  of  the  posterior  portion  of  a  ventral  valve  associated  with  the  specimen  represented  by 
figure  la.     U.  S.  Nat.  Mus.  Cat.  No.  3.5241e. 

If.  Cast  of  the  interior  of  a  ventral  valve  showing  an  unusual  feature  at  y.  This  sijccimen  is  enlarged  in 
figure  Id.     U.  S.  Nat.  Mus.  Cat.  No.  35241d. 

Ig.  Cast  of  the  interior  of  a  dorsal  valve  associated  with  the  specimen  represented  by  figure  la.  U.  S.  Nat. 
Mus.  Cat.  No.  3o241f. 

Ih.  Cast  of  the  interior  of  a  dorsal  valve  associated  with  the  specimen  represented  by  figure  la.  L^.  S.  Nai. 
Mus.  Cat.  No.  35241g. 

li.  Enlargement  of  the  area  shown  in  figure  Ih.     L'.  S.  Nat.  Mus.  Cat.  No.  35241g. 

Ij.  Ventral  valve  tentatively  referred  to  this  species,  from  Locality  88a,  Middle  Cambrian  limestone  at  Dead- 
wood,  Black  Hills,  South  Dakota.     U.S.  Nat.  Mus.  Cat.  No.  51784a. 

Obolus  (Westonia)  stoneanus  (Wliitfield)  (p.  465). 

[I'l.  XLIX.figs.  2and2a.l 

Figure  2.  Cast  of  the  interior  of  a  compressed  ventral  valve.     LT.  S.  Nat.  Mus.  Cat.  No.  51727a. 

2a.  Cast  of  the  interior  of  a  ventral  valve,  showing  a  few  traces  of  the  interior  markings  of  the  shell,     t'.  S. 

Nat.  Mus.  Cat.  No,  51727b. 
2b.  Enlargement  of  a  cast  of  the  area  of  a  ventral  valve.     U.  S.  Nat.  Mus.  Cat.  No.  51727c. 
2c.  Cast  of  the  posterior  portion  of  the  interior  of  a  ventral  valve.     U.  S.  Nat.  Mus.  Cat.  No.  51727d. 
2d.  Enlargement  of  a  portion  of  the  outer  surface  of  a  ventral  valve.     U.  S.  Nat.  Mus.  Cat.  No.  51727e. 
2e.  Cast  of  the  interior  of  a  dorsal  valve.     U.  S.  Nat.  Mus.  Cat.  No.  51727f. 
2f.  Posterior  half  of  a  cast  of  the  interior  of  a  dorsal  valve.     U.  S.  Nat.  Mus.  Cat.  No.  51727g. 
2g.  Cast  of  the  outer  surface  of  a  dorsal  valve.     V.  S.  Nat.  Mus.  Cat.  No.  51727h. 

The  specimens  represented  are  all  from  Locality  85s,  Ujjper  Cambrian  sandstone  at  Prairie  du  Sac,  Sauk  County, 
Wisconsin. 

100 


U.   S.   GEOLOGICAL  SURVEY 


MONOGRAPH   LI     PL.  XXVIII 


FRANCES  WIESER  DEL. 


LIOTVPE   CO   BOSTON 


PLATE   XXIX. 


101 


PLATE  XXIX. 

h.  Central  muscle  sear.  s.  Median  septum, 

i.  TraiisirieJian  muscle  scar.  v.  Visceral  cavity.- 

j.  Anterior  lateral  muscle  scar.  vs.  Main  vascular  sinus. 

LiNGULELLA  FEKRUGiNEA  Salter  (p.  496). 

[ri.  XXX,  fig.  1:  PI.  XXXI,  ngs.  3,  3a-c;  and  PI.  XXXV,  figs.  4,  4a-b.l 

Figure  1.  Cast  of  (he  interior  of  a  ventral  valve  compressed  in  the  shale  of  Division  Ic  of  Matthew  [1886,  p.  82], 

in  New  Brunswick  (locality  not  given).     University  of  Toronto,  Canada.     Specinicii   fi{;urcd  by 

Matthew  [1886,  PI.  V,  fig.  9d]  as  Limjuldla  dawsoni. 
la.  Ventral  and  dorsal  valves  from  Locality  3011,  Middle  Cambrian  .shales  of  Division  Id  of  Matthew  on 

Porters  Brook,  St.  John  County,   New  Brunswick.     University  of  Toronto,  Canada.     Specimens 

figured   by  Matthew  [1880,  PI.  V,  figs.  8,  8a-b]  as  Linguhlla  lingnloides. 
lb  and  Ic.     Ventral  and  dorsal  valves  shown  in  figure  la.     University  of  Toronto,  Canada. 
Id.  Ventral  valve  from  Locality  301k,  Middle  Cambrian,  St.  John  formation  in  St.  John,  Xew  Brunswick. 

Cornell  University,  Ithaca,  N.  Y.     Specimen  figured  by  W'alcott  [1884a,  PI.  V,Tig.  8J  as  Lingulaf 

dawsoni. 
le.  Small  exfoliated  ventral  valve  from  Locality  la.  Middle  Cambrian  shale  on  Manuels  Brook,  Conception 

Bay,  Newfoundland.     U.  S.  Nat.  Mus.  Cat.  No.  51757a. 
If.  Distorted  ventral  valve  from  Localitj-  2,  Middle  Cambrian  shales  on  Manuels  Brook,  Conception  Bay, 

Newfoundland.     U.  S.  Nat.  Mus.  Cat.  No.  56997a. 
Ig.  Cast  of  the  exterior  of  a  distorted  ventral  valve,  associated  with  the  specimen  represented  by  figure  If. 

U.  S.  Nat.  Mus.  Cat.  No.  56997b. 
Ih.  Interior  of  part  of  a  dorsal  valve,  associated  with  specimen  represented  by  figure  If.     U.  S.  Nat.  Mus.  Cat. 

No.  56997c. 
li.  Slightly  distorted  dorsal  valve  as.sociated  with  specimen  represented  by  figure  If.     U.  S.  Nat.  Mus.  Cat. 

No.  56997d. 
]j.  Unusually  convex  and  well-preserved  ventral  A'alve  associated  with  specimen  represented  by  figure  If. 

U.  S.  Nat.  Mus.  Cat.  No.  56997e. 
Ik.  Exfoliated,  slightly  distorted  ventral  valve,  associated  with  specimen  represented  by  figure  If.     U.  S. 

Nat.  Mus.  Cat.  No.  56997f. 
11.  Partly  exfoliated  ventral  valve  from  the   limestones  int<'rbedded  in  the  shales  of  Locality  1,  Middle 

Cambrian,  Manuels  Brook,  Conception  Bay,  Newfoundland.    The  peculiar  appearance  of  what  is 

shown  of  the  interior  of  the  shell  is  partly  explained  by  figure  lo,  which  is  compressed  in  the  shale. 

U.  S.  Nat.  Mus.  Cat.  No.  51756c. 
Im.  Ventral  valve,  associated  with  specimen   represented   by  figure  11.     A  portion  of  the  outer  surface  is 

exfoliated  so  as  to  show  the  characteristic  markings  of  the  inner  surface.     U.  S.  Nat.  Mus.  Cat. 

No.  51756d. 
In.  Cast  of  a  dorsal  valve  showing  the  cast  of  a  median  septum  and  area,  from  Locality  la,  Middle  Cambrian 

sandy  .shale  50  feet  lower  in  the  .section  than  specimens  represented  by  figures  1 1  and  1  in,  on  Manuels 

Brook,  Conception  Bay,  Newfoundland.     L".  S.  Nat.  Mus.  Cat.  No.  517o7b. 
lo.  Cast  of  the  interior  of  a  ventral  valve  showing  the  area  of  a  portion  of  the  ^'isceral  cavity.     From  Locality 

1,  Middle  Cambrian  shale,  Manuels  Brook,  Conception  Bay,  Newfoundland.     V .  S.  Nat.  Mus.  Cat. 

No.  51756a. 
Ip.  Very  nearly  perfect   dorsal  valve,  a.ssocialed  with  the  specimen  represented  by  figure  I  1.     U.  S.  Nat. 

Mus.  Cat.  No.  51756e. 
Iq.  Cast  of  Ihe  interior  of  a  dorsal  valve  associated  with  the  specimen  represented  by  figure  1  1.     U.  S.  Nat. 

Mus.  Cat.  No.  5175Gf. 
Ir.  Interior  of  a  dorsal  valve,  .showing  vascular  sinus  and  median  septum;  also  the  ridges  bounding  the  path  of 

advance  of  the  central  scars.     .\,ssociated  with  the  specimen  represented  by  figure  1 1.     I'.  S.  Nat. 

Mus.  Cat.  No.  51756g. 
Is.  Cast  of  the  interior  of  a  dorsal  valve  from  Locality  1,  Middle  Cambrian  .shale  on  Manuels  Brook,  Concep- 
tion Bay,  Newfoundland.     U.  S.  Nat.  Mus.  Cat.  No.  51756b. 
It.  Ventral  valve,  laterally  compressed,  preserving  the  fine  surface  markings  <lescribed  in  the  text.     Collected 

from  Locality  6g,  Middle  Cambrian  limestone,  Chappie  Arm,  Trinity  Bay,  Newfoundland.     U.  S.  Nat. 

Mus.  Cat.  No.  51759a. 
lu.  Cast  showing  part  of  the  interior  of  a  ventral  valvr  fnmi  Locality  308,  Upper  Cambrian  shales  of  Division 

C3c  of  Matthew's  section  at  Navy  Island,  St.  John  Harbor.  NewBrtuiswick.     I'niversity  of  Toronto. 

The  specimen  represented  by  figure  lu  was  illustrated  by  Matthew  [1892,  PI.  XII,  fig.  8bJ  as  Obulcltaf 

(jemmula. 
102 


U.  S.  GEOLOGICAL  SURVEY 


MONOGRAPH   LI     PL.  XXIX 


FRANCES  WIESER  DEL. 


MELlOTVPE   CO   BOSTON 


PLATE  XXIX.  103 

LiNGULELLA  FERRUGiNEA  Salter — Continued. 

Figure  Iv.  Cast  showing  part  of  the  interior  of  a  dorsal  valve  associated  with  the  specinn-n  n-iiresenled  by  figure  lu. 

The  outlines  of  a  pedicle  groove  were  produced  by  accidental  fractures  in  the  shell.     University  of 

Toronto.     Specimen  illustrated  by  Matthew  [1892,  PI.  Xll,  fig.  8c]  as  Obolella?  gemmula. 
Iw.  Compressed  ventral  valve  associated  with  Obolus  refidgens  in  Locality  308,  Upper  Cambrian  shales  of 

Division  C3c  of  Matthew's  section,  Navy  Island,  St.  Juhn  Harbor,  New  Brunswick.     University  of 

Toronto. 
2.  ^■eut^al  ?  valve  from  Locality  318h,  Middle  Cambrian  shales  at  St.  Da\ids,  South  Wales.     Copied  from 

Ilicks's  figure  [Salter  and  Hicks,  18G7,  fig.  2,  p.  340]  of  Lingulella  femiginea  oralis. 
2a.  Enlarged  view  of  the  valve  represented  by  figure  2.     Copied  from  Salter  and  Hicks  [1867,  fig.  3,  p.  340]. 
2b.  Ventral  valves  from  Locality  318j,  Middle  Cambrian  at  Pen-y-pleidiau,  St.  David.s,  South  Wales.     Copied 

from  Salter's  figure  [Salter  and  Hicks,  1867,  fig.  1,  p.  340]  of  Limjitlclla/a-niginea.     It  represents  the 

type  specimen. 
2c.  Ventral?  valve  from  Locality  318v,  Upper  Cambrian,  Rhiwfelyn,  North  Wales.      Copied  from  Davidson 

[1868,  PI.  XV,  fig.  7a].  " 
2d.  Ventral  valve  from  Locality  318u,  Upper  Cambrian,  Gwerny-y-Barcud,  Norlh  Wales.   Cupied  from  David- 
son [1868,  PI.  XV,  fig.  6a]. 
2e.  Distorted  ventral  valve  from  Locality  366b,  Middle  Cambrian  at  Porlhclais  Harbor,  .south  of  St.  Davids, 

South  Wales.     Copied  from  Davidson  [1871,  PI.  XLIX,  fig.  3.5a]. 
2f.  Distorted  veptral  valve  from  Locality  318h,  Middle  Cambrian  Menevian  shales  at  St.  Davids,  South  Wales. 

Copied  from  Davidson  [1871,  PI.  XLIX,  fig.  33a]. 

Lingulella  billingsiana  (Whiteaves)   (j).  4S3). 

Figure.?  3  and  3a.  Ventral  valves,  from  Locality  314a,  Upper  Cambrian  shales  on  Kelleys  Island,  Conception  Bay, 
Newfoundland.  Drawn  from  the  type  material  in  the  Museum  of  the  Geological  Survey  of  Canada. 
Whiteaves  [1878,  p.  226]  did  not  figure  the  specimens  on  which  he  based  his  species.  Figure  3a 
may  be  taken  as  the  type. 

Lingulella  buttsi  Walcott  (p.  484). 

Figure  4.  Dorsal  valve,  the  type  specimen,  from  Locality  90c,  Middle  Cambrian  Conasauga  limestone  near  Kimbrel, 
Bibb  County,  Alabama,  showing  the  slight  median  flattening  of  the  surface  and  backward  curvature 
of  the  concentric  striae.  U.  S.  Nat.  Mus.  Cat.  No.  51779a.  Copied  from  Walcott  [1908d,  PI.  VIII, 
fig.  6]. 

4a  and  4a'.  Exterior  view  and  side  outline  of  ventral  valve  from  Locality  90b,  Middle  Cambrian  Conasauga 
limestone  near  Woodstock,  Bibb  County,  Alabama.     U.  S.  Nat.  Mus.  Cat.  No.  51778a. 

4b  and  4b'.  Partly  exfoliated  ventral  valve  associated  with  the  shell  represented  by  figure  4a,  showing  the 
cast  of  the  ridges  along  the  path  of  advance  of  the  muscle  scars  on  each  side  of  the  \'isceral  area. 
U.  S.  Nat.  Mus.  Cat.  No.  51778b. 

Delgadella  lusitanica  (Delgado)   (p.  500). 

Figure  5.  Cast  of  the  interior  of  a  ventral  valve,  the  type  specimen.     The  marginal  rim  indicates  the  thickness  of 
the  shell. 
5a.  Cast  of  the  interior  of  a  ventral  valve. 
5b.  Cast  of  a  ventral  valve. 

The  specimens  represented  are  all  from  Locality  351,  Lower  Cambrian  shales  at  Monte  de  Valbom,  northeast  of 
Villa  Boim,  Province  of  Alemtejo,  Portugal.  The  figures  (5,  5a,  and  5b)  are  reproduced  from  photographs  sent  to  me 
by  M.  Delgado  of  the  specimens  figured  by  him  [1904,  PI.  IV,  figs.  34,  31,  and  32,  respectively]  under  the  name  of 
Lingulepis  lusitanica.     Each  of  the  views  in  this  monograph  is  the  reverse  of  the  corresponding  one  given  by  Delgado. 

Lingulella  delgadoi  Walcott  (p.  491). 

Figure  6.  Cast  of  exterior  of  ventral  valve,  the  type  specimen. 
6a.  Cast  of  interior  .of  ventral  valve. 

Figures  6  and  6a  are  reproduced  from  photographs  sent  to  me  by  M.  Delgado  of  the  specimens  figured  by  him 
[1904,  PL  IV,  figs.  16  and  18,  respectively]  under  the  name  of  Lingulella  granvillensis. 

Figure  6b.  Cast  of  dorsal  valve  showing  exterior  surface.  Reproduced  from  a  photograph  sent  to  me  by  M.  Delgado 
of  the  specimen  figured  by  him  [1904,  PI.  IV,  fig.  27]  under  the  name  of  Lingulepis  acuminata  meeki. 
The  -^dew  in  this  monograph  is  the  reverse  of  that  given  by  Delgado. 
6c.  Cast  of  shell  of  dorsal  valve  partly  broken  away.  Reproduced  from  a  photograph  sent  to  me  by  M.  Delgado 
of  the  specimen  figured  by  him  [1904,  PL  IV,  fig.  14]  under  the  name  of  Lingulella  cf.  liyiguloides. 
The  view  in  this  monograph  is  the  re\'erse  of  that  given  by  Delgado. 

The  specimens  represented  by  figures  6,  6a-c  are  from  Locality  351,  Lower  Cambrian  shales  at  Monte  de  Valbom, 
northeast  <if  Villa  Boim,  Province  of  Alemtejo,  Portugal. 


PLATE   XXX. 


105 


PLATE  XXX. 

LixGULELLA  FERKUGixEA  Salter?  (p.  496). 

|M.  XXIX,  figs.  1,  la-w,  2,  2a-f;  I'l.  XXXI,  figs.  :!,  3a-c-;  and  I'l.  X.KXV,  fiKS.  4,  Ja-b.] 

FiGURK  i.  \enlral  valv&s  from  Locality  389d,  Upper  Cambrian,  at  Iruya,  Salta,  Argentina.     Copied  from  Kayser'e 
figure  [1897,  PI.  VII,  fig.  7]  of  LinguhUn  ci./erruginea. 

LiNGULELLA    DAVLSI    (McCov)    (]).   489). 
[PI.  XX.XI,  figs.  6.  la-h.) 

Figure  '.;.  Dorsal  valve,  from  Locality  389d,  Upper  Cambrian,  at  Iriiya,  Salta,  Argentina.     Copied  from  Kayser  [1897, 
PI.  VII,  fig.  6]. 
2a.  Ventral  and  dorsal  valves  from  Locality  332,  I'lipor  Cambrian  limestone  at  Saimaki,  Liaotung,  China. 
Copied  from  Kayser  [1883,  PI.  Ill.'fig.  3]. 

LixGULELLA  NiCHOLSONi  Callawav  (p.  522). 

Figure  .3.  Ventral  valve,  the  type  specimen,  from  Locality  3041,  Upper  Cambrian  Shineton  shales  in  South  Shrop- 
shire, England.     Copied  from  Callaway  [1877,  PI.  XXIV,  fig,  11]. 
3a.  Enlargement  of  the  area  of  a  ventral  valve  from  one  of  the  localities  mentioned  in  Locality  3041,  South 

Shropshire,  England.     Copied  from  Callaway  [1877,  PI.  XXIV,  fig.  lib]. 
3b.  Dorsal  valve  with  outer  shell  exfoliated  except  over  the  area.     V.  S.  Xat.  Mus.  Cat.  Xo.  5174Sa. 
3c.  Exfoliated  dorsal  valve.     The  central  and  transmedian  muscle  scars  are  drawn  from  another  specimen. 

U.  S.  Nat.  Mus.  Cat.  Xo.  5174Sb. 
3d.  A  small  ventral  valve  showing  outline  of  area.     L^.  S.  Xat.  Mus.  Cat.  Xo.  51748c. 
3e.  A  small  elongate  dorsal  valve.     U.  S.  Nat.  Mus.  Cat.  No.  5174Sd. 

3f .  A  small  ventral  valve  resting  on  the  dorsal  valve  which  has  been  pushed  backward  out  of  its  natural 
position.     U.  S.  Nat.  Mus.  Cat.  Xo.  51748e. 
The  specimens  represented  by  figures  3b-f  are  from  Locality  304  1,  I'pper  Cambrian  Shineton  shale,  on  Shineton 
Brook  and  vicinity,  South  Shropshire,  England. 

LiNGtTLELLA    cf.    FEREUGIXEA    (]).  500). 

Figure  4.  \'entral  valve  from  Locality  345,  Middle  Cambrian  shale  on  the  Dlouhd  Ilora,  near  Skrej,  Bohemia.  Copied 
from  Pompeckj's  figure  [189(ib,  PI.  XIV,  figs.  16a-b]  of  " Lingulella  {?)  sp." 

LiNGULELLA    KltJEENSIS    (WaagCIl)   (p.  511). 

Figure  5.  Type  specimen  of  Waagen's  species  "Lingula  warthi."  Geol.  Survey  India  Cat.  Xo.  3/79.5.  Specimen 
figured  by  Waagen  [18S5,  PI.  LXXX^'I,  figs.  9a-b]  as  Lingula  (?)  tfarlhi.  The  same  specimen 
is  figured  by  Waagen  [1891,  PI.  II,  figs.  17a-b]  as  Lingula  (f)  Hurensis,  hut  from  his  description 
[1885,  pp.  769-770]  this  is  the  form  to  which  he  intended  to  give  the  name  uarthi.  I  think  it  is  the 
dorsal  valve  of  Lingulella  Hurensis. 

5a.  Copy  of  the  figures  given  by  Waagen  [1891,  PI.  II,  figs.  17a-b]  of  the  specimen  represented  by  figure  5. 
The  cardinal  slopes  are  crushed  in,  which  gives  the  depressed  slopes  described  by  '\^'aagen  [1885, 
p.  769].     The  front  is  also  restored. 

6.  Type  specimen  of  Lingula  (f)  hiurensis  Waagen.  Geol.  Survey  India  Cat.  Xo.  3794.  Specimen  figured 
by  Waagen  [1SS5,  p.  768,  PI.  LXXXVI,  figs.  Sa-b]  as  Lingula  (?)  hiurensis.  The  same  specimen  is 
figured  by  Waagen  [1891,  PI.  II,  figs.  ISa-b]  as  Lingula  (f)  warthi,  but  from  his  description  [1885, 
p.  768]  this  is  the  form  to  which  he  intended  to  give  the  name  Hurensis. 

6a.  Copy  of  the  figures  given  by  Waagen  [1891,  PI.  II,  figs.  18a-b]  of  the  specimen  represented  in  figure  6.    The 
front  of  the  shell  is  restored  in  \\'aagen's  figures,  and  the  cardinal  slopes  widened  out  so  as  to  make  a 
diagrammatic  figure. 
The  specimens  represented  are  both  from  Locality  357.  Middle  Cambrian  limestones  in  the  Xeobolus  beds  of  the 
Khussak  group,  near  Kiiira,  Salt  Range,  India. 

LiXGILELLA   AVIRTHI    (BaiTaiicle)  (p.  541). 

Figure  7.  \'entral  valve  from  Locality  303c,  passage  beds  between  the  Upper  ('aml)rian  and  Ordovician  near  Hof, 
Bavaria.     Enlarged  one-third.     Type  specimen,  copied  from  Barrande  [1868a,  fig.  63]. 

LiNGULELLA  CEDENS  (BaiTande)  (p.  485). 

Figure  8.  Ventral  valve  from  Locality  303c,  passage  beds  between  the  Upper  Cambrian  and  (Jrdnvician  near  Hof, 
liavaria.     Enlarged  unc-third.     Tvpe  specimen,  copied  from  Barrande  [lS6Sa,  fig.  CO]. 
106  ■ 


U.  S.  GEOLOGICAL  SURVEY 


MONOGRAPH   LI     PL.  XXX 


19' 


FRANCES  WtESER  DEL. 


rtELIOTVoe    CO    BOSTON 


PLATE  XXX.  107 

LiNGULELLA?    (LiNGULEPIS  ?)    SQUAMOSA    (Holl;    (p.  559). 

Figure  9.  Ventral  valve  from  Locality  304g,  Upper  Cambrian  Hollybush  sandstones,  Malvern  Hills,  England.     Copied 
from  Davidson's  figure  [1S6G,  PI.  II,  fig.  7]  of  Lingula  squamosa. 

LiNGULELLA    (LiNGULEPIS?)    PYGM^A    (Salter)    (p.  556). 

Figure  10.  Ventral?  valve  from  Locality  304f,  Upper  Cambrian  "Black  shales,"  Malvern  Hills,  England.  Copied 
from  Salter  [186.5,  figs.  8a-b,  p.  101]. 

LiNGULELLA  siGNATA  (Barraiide)  (p.  532). 

Figure  11.  Dorsal?  valve  from  Locality  303c,  passage  beds  between  the  Upper  Cambrian  and  Ordovician  near  Ilof, 
Bavaria.     Enlarged  one-third.     Copied  from  Barrande  [1868a,  fig.  73]. 

LiNGULELLA?  IIUMILLIMA  (BaiTaiide)   (p.  507). 

Figure  12.  Dorsal  valve  from  Locality  303c,  passage  beds  between  the  Upper  Cambrian  and  Ordovician  near  Hof, 
Bavaria.     Enlarged  one-third.     Copied  from  Barrande  [1868a,  fig.  70]. 

LiNGULELLA  sp.  undt.  a  Walcott  (p.  541). 

Figure  13.  Dorsal  valve  from  Locality  310k,  Upper  Cambrian  limestone  on  Oeland  Island,  Sweden.  IT.  S.  Nat.  Mus. 
Cat.  No.  .517-19a. 

LiNGULELLA    LINNARSSONI    (Walcott)    (p.  516). 

Figure  14.  Ventral  valve,  the  type  specimen,  with  the  outer  shell  partly  exfoliated.    U.  S.  Nat.  Mus.  Cat.  No.  3.52.57a. 
14a.  Enlargement  of  the  exterior  surface  on  the  anterior  portion  of  a  ventral  valve.    L".  S.  Nat.  Mus.  Cat.  No. 
3.5257b. 
The  specimens  represented  are  both  from  Locality  320n,  Middle  Cambrian  limestone  at  Lovened,  Djupadal, 
Province  of  Skaraborg,  Sweden. 

LiNGULELLA  AGNOSTORUM   (WalleHus)    (p.  476). 

Figure  15.  Ventral  valve  greatly  enlarged,  and  longitudinal  outline  of  valve,  from  Localitj-  3101,  passage  beds  between 
the  Middle  and  Upper  Cambrian,  at  Borgholm,  Oeland  Island,  Sweden.  U.  S.  Nat.  Mus.  Cat.  No. 
51747a. 

Obolus  ?  zoppi  Walcott   (p.  422). 

Figure  16.  Ventral  valve,  the  type  specimen,  from  Locality  354f,  Middle  Cambrian  sand.stone  nrar  Canal  Grande,  on 
the  road  to  Punta  Pintau,  Sardinia,  Italy.     Copied  from  Bornemann  [1891,  PI.  XIX,  fig.  17a]. 

16a.  Dorsal  valve  associated  w-ith  the  shell  represented  by  figure  16.  Copied  from  Bornemann  [1891,  PI.  XIX, 
fig.  16]. 

16b.  Side  \'iew  of  the  shell  represented  in  figure  16.     Copied  from  Bornemann  [1891,  PI.  XIX,  fig.  17b]. 

Obolus  ?  meneghinii  Walcott  (p.  403). 

Figure  17.  A  small  exfoliated  ventral  valve,  the  type  specimen,  from  Locality  354c,  Middle  Cambrian  .sandstone  at 
Punta  Pintau  (Canal  Grande),  Sardinia.     Copied  from  Bornemann's  figure  [1891,  PI.  XIX,  fig.  14a]  of 
Lingula  pctalon. 
17a.  A  large  ventral  valve  from  Locality  354e,  Middle  Cambrian  shale  at  Porto  Canal  Grande,  Sardinia. 
Copied  from  Bornemann's  figure  [1891,  PI.  XIX,  fig.  18]  of  OboleUa  sp. 

LiNGULELLA    BORNEMANNI    (Walcott)     (p.  483). 

Figures  18,  18a,  and  18b.  More  or  less  distorted  and  compressed  ventral  valves  from  Localil  y  354,  Middle  ?  Cambrian, 
Canal  Grande,  Sardinia. 
Figures  18,  18a,  and  ISb  are  copied  from  Bornemann's  figures  [1891,  PI.  XIX,  figs.  10a,  4,  and  8,  respectively]  of 
Lingula  attenuata.     Figure  18  represents  the  type  specimen. 

Figure  18c.  Dorsal  ?  valve  from  Locality  354,  Middle  ?  Cambrian,  Canal  Grande,  Sardinia.  Copied  from  Bornemann's 
figure  [1891,  PI.  XIX,  fig.  7]  of  Lingula  attenuata. 


108  PLATE  XXX. 

Obolus  schmalenseei  (Walcott)   (p.  412). 

Figure  19.  Broad  form  of  the  ventral  valve,  showing  cast  of  pedicle  furrow  and  a  portion  of  the  visceral  cavity.    U.  S. 

Nat.  Mus.  Cat.  No.  35291a. 
19a.  Exterior  of  dor.sal  valve.     U.  S.  Nat.  Mu.s.  Cat.  No.  35291b. 
19b.  An  elongate  ventral  valve.     U.  S.  Nat.  Mus.  Cat.  No.  35291c. 
19c.  Cast  of  a  dorsal  valve,  showing  the  strongly  marked  area  and  niarginsof  the  posterior  portion  of  the  visceral 

ca\-ity.     U.  S.  Nat.  Mus.  Cat.  No.  3529Jd. 
19d.  Partly  exfoliated  ventral  and  dorsal  valves,  the  type  specimen.     U.  S.  Nat.  Mu.s.  Cat.  No.  3529Ie. 
19e.  A  small  ventral  valve.     U.  S.  Nat.  Mus.  Cat.  No.  3.5291f. 

The  specimens  represented  are  all  from  Locality  8w,  Middle  Cambrian  limestone  at  Andrarum,  Province  of 
Christianstad,  Sweden. 

Elkania  IDA  (Billings)  (p.  56.3). 

[PI.  Ll,  figs.  4,  4a-c.l 

Figure  20.  A  probable  ventral  valve,  from  Locality  319,  Lower  Ordo^^cian  limestone  of  No.  1  of  Billings's  section,  Point 
Le\as,  Quebec,  Canada.     Geol.  Survey  Canada. 
20a.  Dorsal  valve  from  the  locality  represented  by  figure  20.     Geol.  Survey  Canada. 


PLATE    XXXI. 


109 


PLATE  XXXI. 


a.  Central  lateral  space  of  area, 
a'.  Outer  lateral  space  of  area. 
c.  Trapezoidal  area,  including  central,  middle 

lateral,  and  outside  lateral  muscle  scars. 
f.  Flexure  line  of  area, 
h.  Central  muscle  scar. 


I.  Transmedian  muscle  scar. 

j.  Anterior  lateral  muscle  scar. 

1.  Outside  lateral  muscle  scar, 
p.  Pedicle  groove. 
V.  Visceral  cavity, 
vs.  Main  vascular  sinus. 


LixGULELLA  NATHORSTi  Linnarssoii  (p.  521). 

Figure  1,  Cast  of  the  interior  of  ventral  valve,  from  Locality  320x,  Lower  Cambrian  lime.stonn  at  Andrariim,  Province 

of  Christ ianstad,  Sweden.     U.  S.  Nat.  Mtis.  Cat.  No.  18109a. 
la  and  lb.  Casts  of  the  interior  of  dorsal  valves  associated  with  (he  speeimen  represented  by  figure  1.     U.  S. 

Nat.  llus.  Cat.  Nos.  18199b  and  18199c,  respectively. 
Ic.  Ventral  valve  preserving  most  of  the  shell,  from  I-ocality  8y,  Lower  Cambrian  limestone  at  Skirosen, 

Dalarne,  Sweden.     U.  S.  Nat.  Mus.  Cat.  No.  517;»a. 
Id  and  le.  Dorsal  valves  associated  with  the  ventral  valve  represented  by  figure  Ir.     IT.  S.  Nat.  Mus.  Cat. 

Nos.  51739b  and  51739c,  respectively. 
If.  Ventral  valve  associated  with  the  ventral  valve  represented  by  figure  Ic.    U.  S.  Nat.  Mus.  Cat.  No.  51739d- 
Ig  and  Ih.  Dorsal  valves  associated  with  the  ventral  valve  represented  liy  figure  Ic.     U.  S.  Nat.  Mus.  Cat.  Nos. 

51739eand  517301,  respectively. 

LiNGULELLA    SIEMIKADZKII    (W^alcott)    (p.  5.31). 

Figure  2.  Ventral  valve,  the  type  specimen,  showing;  portion  of  the  outer  surface  and  the  finely  striated  inner  layer 
of  shell.     U.  S,  Nat.  Mus.  Cat.  No.  3525Sa. 
2a.  Cast  of  part  of  a  dorsal  valve.     U.  S.  Nat.  Mus.  Cat.  No.  3525Sb. 

The  specimens  represented  are  both  from  Locality  368,  Middle  Cambrian  quarlzitic  sandstones  in  the  Pepper  Moun- 
tains, near  Sandomierz,  on  the  Vistula,  Russian  Poland. 

LiNGULELLA    FEREUGINEA    Salter  (p.  406). 
[PI.  XXIX.  tigs.  1,  la-w,  2,  2a-f;  PI.  XXX,  fig.  1:  and  PI.  XXXV,  figs.  4,  Ja-b.J 

Figure  3.  Ventral  valve  from  Locality  310p,  Middle  Cambrian  limestone  at  Borgholm,  Oeland  Lsland,  Sweden, 
U.  S.  Nat.  Mus.  Cat.  No.  51752a. 

3a.  Dorsal  valve  from  Locality  310y,  Middle  Cambrian  limestone  of  Kiviks  Esperod,  Province  of  Malmohus, 
Sweden.     V.  S.  Nat.  Mus.  Cat.  No.  18205a. 

3b.  Short  ventral  valve  from  Locality  310z,  Middle  Cambrian  limestone  at  Brantevik,  Sweden,  that  is  doubt- 
fully referred  to  this  species.     U.  S.  Nat.  Mus.  Cat.  No.  51750a. 

3c.  Ventral  valve  doubtfully  referred  to  the  species  from  Locality  330m,  Middle  Cambrian  at  Kinnekulle, 
Province  of  Skaraborg,  Sweden.  Copied  from  Linnarsson's  figure  [1876,  PL  III,  fig.  28]of  "Xtn^u^a 
or  Ling'ileUa  sp." 

LixGi'LELLA  LEPi.s   (Salter)  (p.  514). 

Figure  4.  Ventral    valve    from    Locality    366k,    Upper    Cambrian  shales,  Penmorfa,  Jlerioneth.shire,  North  Wales. 

Enlarged  drawing  of  the  specimen  represented  in  figure  4a.     Copied  from  Davidson  [1871,  PL  XLIX, 

fig.  31a]. 
4a.  The  ventral  valve  figured  in  figure  4,  natural  size.     Copied  from  Davidson  [1871,  PI.  XLIX,  fig.  31]. 
4b.  Cast  of  the  interior  of  a  ventral  valve  from  Locality  8x,  pas.sage  beds  between  the  I'jiper  Cambrian  and  the 

Ordovician,  at  Slemmestad,  near  Chrisliania,  Norway,  showing  area,  cast  of  pedicle  groove,  and 

visceral  cavity.     U.  S.  Nat.  Mus.  Cat.  No.  51741a. 
4c.  Exterior  of  a  strongly  convex,  highly  polished  ventral  valve  associated  with  tlie  shell  represented  in  figure 

4b. .  Traces  of  radiating  ribs,  so  strongly  developed  in  figure  4d,are  visible  with  a  strong  lens.    U.  S. 

Nat.  Mus.  Cat.  No.  51741b. 
4d.  Dorsal  valve  associated  with  the  shell  represented  in  figure  4b.  marked  by  strong  radiating  ribs  and  fine 

concentric  slriie.     I^.  S.  Nat.  Mus.  Cat.  No.  51741c. 
4e.  Narrow  form  of  donsal  valve,  showing  outline  of  elongate  visceral  cavity,  from  Locality  9f,  Upper  Cambrian 

limestones  at  Ncrrsnies,  west  of  Christiania,  Norway.     U.  S.  Nat.  Mus.  Cat.  No.  51742a. 
4f.  Cast  of  part  of  a  broad  form  of  a  dorsal  valve  associated  with  the  shell  represented  by  figure  4b.     U.  S. 

Nat.  Mus.  Cat.  No.  51741d. 
110 


U.  S.   GEOLOGICAL  SURVEY 


MONOGRAPH   LI     PL.  XXXI 


FRANCES  WIESER  DEL. 


riCLlOTVPE    ;0   SSSTON 


PLATE  XXXI.  Ill 

LiNGULKLLA?    PRIM^VA    Hicks   (p.  527). 

Figures  5  and  5a.  Ventral?  valves  from  the  Middle?  Cambrian  Cacrfai  group  (see  Locality  366c),  soulh  of  ,Si. 
Davids,  South  Wales.  Copied  from  Davidson  [ISKIi,  PI.  XVII,  figs.  .31  and  3.3,  respectively].  Figure 
oa  represents  the  type  specimen,  Davidson's  figure  being  a  copy  of  the  one  given  by  liicks  [1871, 
PI.  XV,  tig.  1-1]. 

LiNGXJLELLA  DAVisi   (McCoy)  (p.  489). 

[PI.  XXX,  figs.  2  and  2a.] 

Figures  6  and  6a.  Distorted  ventral  valves  from  "Lingula  flags,  Penmorfa,  Tremadoc"  (see  localities  366k  and  366 1;, 
Merionethshire,  North  Wales.     Copied  from  Davidson  [IStiG,  PI.  IV,  figs.  10  and  11,  respectively]. 

6b.  Distorted  ventral  valve  from  Locality  317b,  Middle  Cambrian,  at  Bellewstown,  County  Meath,  Ireland. 
Copied  from  Davidson  [1866,  PI.  IV,  fig.  12]. 

6c.  Enlargement  of  the  area  of  a  cast  of  a  ventral  valve  from  Locality  366a,  Upper  Cambrian  shales,  6  miles  east 
of  Ffestiniog,  Merionethshire,  North  Wales.     U.  S.  Nat.  Mus.  Cat.  No.  51740a. 

6d.  Cast  of  the  interior  of  a  distorted  ventral  valve  associated  with  the  specimen  represented  by  figure  6c. 
r.  S.  Nat.  Mus.  Cat.  No.  51740b.  Specimen  figured  by  Walcott  [189Sb,  PI.  XXVII,  fig.  2]  asObobjs 
[Lingulella)  davisii. 

Be.  Cast  of  the  interior  of  a  dorsal  valve,  showing  the  characteristic  muscle  scars  of  the  genus.  Locality  366n, 
Upper  Cambrian  shales  at  Portmadoc,  Merionethshire,  North  Wales.  U.  S.  Nat.  Mus.  Cat.  No. 
35239a.     Specimen  figured  by  Walcott  [1898b,  PI.  XXVII,  fig.  4]  as  Obolus  {Lingulella)  davisii. 

6f.  Cast  of  the  interior  of  a  ventral  valve  a.ssociated  with  the  shell  represented  in  figure  6e,  showing  the  out- 
lines of  the  visceral  cavity  and  the  vascular  sinuses.  U.  S.  Nat.  Mus.  Cat.  No.  35239b.  Specimen 
figured  by  Walcott  [1898b,  PI.  XXVII,  fig.  1]  as  Obolus  (Lingulella)  davisii. 

6g.  Cast  of  the  interior  of  a  ventral  valve  in  which  the  characteristic  punctate  surface  of  the  interior  of  the  shell 
is  shown  by  the  large  pajjillae  scattered  over  the  surface.  Locality  366a,  Upper  Cambrian  shales  6 
miles  east  of  Ffestiniog,  Merionethshire,  North  Wales.     U.  S.  Nat.  Mus.  Cat.  No.  51740c. 

6h.  Cast  of  a  distorted  dorsal  valve  associated  with  the  shell  represented  in  figure  6g,  preserving  the  impressions 
of  the  transmedian  and  outside  lateral  muscle  scars.  U.  S.  Nat.  Mus.  Cat.  No.  51740d.  Specimen 
figured  by  W'alcott  [1898b,  PI.  X'XVII,  fig.  5]  as  Obolus  (Lingulella)  davisii. 


PLATE    XXXII. 


62667°— VOL  51,  pt  2—12 8  113 


PLATE  XXXII. 

h.  Central  muscle  scar.  j.  Anterior  lateral  muscle  scar. 

LiNGULELLA  DAViDSONi  (Barrancle)  (p.  489). 
Figure  1.  Partly  exfoliated    ventral    valve,  the   type   specimen,  showing  lamellated   shell,  from  Locality  303m, 

Ordovician,  Etage  d4,  at  Lieben,  Bohemia.     Enlarged  one-third.     Copied  from  Barrande  [1879b, 

PI.  CIV,  fig.  vni:lA]. 
la.  Side  view  of  the  specimen  represented  by  figure  1.     Copied  from  Barrande  [1879b,  PI.  CIV,  fig.  viii:lb]. 
lb.  Less  elongate  ventral  valve  than  that  represented  by  figure  1,  from  Locality  303n,  Ordovician,  Etage 

d4,  at  Wraz,  Bohemia.     Enlarged  one-third.     Copied  from  Barrande  [ISTOb,  PI.  CIV,  fig.  vin:.3A]. 
Ic.  Side  view  of  the  specimen  represented  by  figure  lb.     Copied  from  Barrande  [1879b,  PI.  CIV,  fig.  viii:3b]. 
Id.  Enlargement  of  the  area  and  posterior  portion  of  figure  le.     Copied  from  Barrande  [1879b,  PI.  CIV,  fig. 

vm:4E]. 
le.  Interior  of  a  ventral  valve  from  Locality  303o,  Ordovician,  Etage  d4,  at  Lodenitz,  Bohemia.     Copied  from 

Barrande  [1879b,  PI.  CIV,  fig.  vni:4]. 

LiNGULELLA?  iNsoNS  (Barrande)  (p.  508). 

Figure  2.  Interior  of  ventral  valve  from  Locality  303d,  Lower  Ordovician,  Etage  dl,  at  Swarow,  Bohemia.  Copied 
from  Barrande  [lS79b,  PI.  CV,  fig.  .x:4A]. 

2a.  Partly  exfoliated  dorsal  valve  from  same  bed  as  specimen  represented  by  figure  2.  Copied  from  Bar- 
rande [1879b,  PI.  CV,  fig.  x:3A]. 

2b  and  2c.  Interior  of  ventral  valves,  showing  area,  from  Locality  303e,  Lower  Ordovician,  Etage  dl,  at  Sta. 
Benigna,  Bohemia.  Copied  from  Barrande  [1879b,  PL  CV,  figs.  x:5A  and  x:CA,  respectively]. 
Figure  2c  represents  the  type  specimen. 

2d.  Enlargement  of  the  area  of  figure  2c.     Copied  from  Barrande  [1879b,  PL  CV,  fig.  x:6E]. 

2e.  Enlargement  of  surface  of  shell  and  impression  of  interior  surface  from  the  anterior  portion  of  the  valve. 
Locality  303d,  Lower  Ordovician,  Etage  dl,  at  Swarow,  Bohemia.  Copied  from  Barrande  [lS79b, 
PL  CV,  fig.  x:lf]. 

LiNGULA?  EXiMiA  Barrande  (p.  301). 
Figure  3.  Fragment  of  the  shell  greatly  enlarged  to  show  complex  character  of  the  surface  ornamentation.     Inserted 
for  comparison.     Locality  3031,  Lower  Ordovician,  Etage  dl,  at  Libetschov,  Bohemia.     Copied  from 
Barrande  [lS79b,  PI.  CV,  fig.  i:f]. 

LiNGULELLA?  SIMPLEX  (BaiTaiide)  (p.  534). 

Figure  4.  Ventral  valve  showing  portion  of  area  where  the  tliin  shell  has  been  pressed  down  into  it.  Locality  303p, 
Lower  Ordovician,  Etage  d3,  near  Beraun,  Bohemia.  Copied  from  Barrande  [lS79b,  PI.  CIV,  fig. 
vi:lA]. 

4a.  Dorsal  valve  from  Locality  303a,  Lower  Ordovician,  Etage  d3,  at  Trubin,  Bohemia.  Copied  from  Bar- 
rande [1879b,  PL  CIV,  fig.  vi:4A]. 

4b.  Side  view  of  specimen  represented  by  figure  4a.     Copied  from  BarnuKle  [lS79b,  PI,  t'lV,  fig.  vi:4B]. 

Obolus  (Paljeobolu.'^ )  BRETONENSis   (Matthew)  (p.  426). 

Figure  5.  Cast  of  the  interior  of  a  flattened  ventral  vah-e,  the  type  specimen,  slightly  compressed  laterally.    I'niversity 
of  Toronto,  Canada.     Reproduced  from  a  photograph  of  one  of  Matthew's. specimens;  it  may  be  the  one 
used  by  him  in  drawing  figure  2b  of  his  paper  [1903,  PI.  IX],  but  closer  identification  is  impossible. 
5a.  Cast  of  part  of  the  interior  of  a  ventral  valve.     University  of  Toronto,  Canada. 

5b.  Exterior  of  a  nearly  entire  dorsal  valve.     University  of  Toronto,  Canada.     Reproduced  from  a  photograph 
of  one  of  JIatthew's  specimens;  it  may  be  the  one  used  by  him  in  drawing  figure  2(1  of  his  paper 
[1903,  PL  IX]. 
5c.  Exterior  of  a  dorsal  valve,  showing  finely  preserved  outer  surface.     University  of  Toronto,  Canada.     Repro- 
duced from  a  photograph  of  one  of  Matthew's  specimens;  it  may  be  the  one  used  by  him  in  drawing 
figure  2a  of  his  paper  [1903,  PI.  IX]. 
5d.  Cast  of  part  of  a  broken  dorsal  valve  in  which  the  area  is  preserved.     University  of  Toronto,  Canada. 
5e.  Enlargement  of  a  cast  of  the  interior  of  a  dorsal  valve.     L^niversity  of  Toronto,  Canada.     Reproduced  from 
a  photograph  of  one  of  Matthew's  specimens;  it  may  be  the  one  used  by  him  in  drawing  figure  2e  of  his 
paper  [1903,  PI.  IX]. 
The  exact  locality  represented  by  the  specimens  figured  is  not  known.     It  is  probable,  however,  that  ihey  were 
all  collected  at  the  type  locality  (344b),  Middle  Cambrian  shales  of  Division  E3d  of  Matthew's  Etcheminian,  Dugald 
Brook,  Cape  Breton,  Nova  Scotia. 

Figures  .Sf  and  og.  Exterior  of  nearly  perfect  ventral  and  dorsal  valves,  from  Locality  lOp,  Middle  Cambrian  sand- 
stones of  Division  E2b  of  Matthew  on  Dugald  Brook,  Cape  Breton,  Nova  Scotia.     U.  S.  Nat.  Mus. 
Cat.  Nos.  51664a  and  ■■)1664b,  respectively. 
114 


U,  S.  GEOLOGICAL  SURVEY 


MONOGRAPH   LI     PL.  XXXII 


FRANCES  WIESER  DEL. 


LIOTVPC     CO     BOS1 


PLATE    XXXIII. 


115 


PLATE  XXXIII. 

LiNGULELLA  LENS  (Matthew)   (p.  512). 

Figure  1.  ^"entral  valve  broken  and  embedded  in  limestone.     University  of  Toronto,  Canada.     TjTie  epecimen, 

figured  by  Matthew  [1901,  PI.  V,  fig.  3a]  as  Lingula  f  lens. 
la.  Ventral  valve  showing  outline  of  a  smaller  shell  than  that  rf'jire.^ontcd  by  figure  1.     U.  S.  Nat.  Mus.  Cat. 

No.  51767a. 
lb,  Ic,  and  Id.  Partly  e.xfoliated  dorsal  valves  varying  somewliat  iii  oulliue  and  size.     V.  S.  Nat.  Mus. 

Cat.  Nos.  517G7b,  5]7f)7c,  and  51767d,  respectively. 

The  specimens  represented  are  all  from  Locality  lOr,  Upper  Camlirian  slialcs  of  Division  C3a?  of  Matthew,  at 
McAdam  Shore,  East  Bay,  Cape  Breton,  Nova  Scotia. 

LiNGULELL.v  coNCixx.A.  Mattliew  (p.  4S6). 

(PI.  XXXIV,  figs.  1,  la-r.] 

Figure  2.  Ventral  valve  broadened  by  movement  in  the  fine  shalo  of  Locality  3h,  Upper  Cambrian,  McNeil  Brook, 

Cape  Breton,  Nova  Scotia.     U.  S.  Nat.  Mus.  Cat.  No.  51762s. 
2a.  Ventral  valve  that  occurs  on  the  same  hand  specimen  with  the  shell  represented  by  figure  2.     It  has  been 

elongated  by  the  movement  which  broadened  figure  2.     V.  S.  Nat.  Mus.  Cat.  No.  51762t. 
2b.  ^'entral  valve  associated  with  the  shell  represented  by  figure  2,  preserving  its  original  outline.    U.  S. 

Nat.  Mus.  Cat.  No.  51762u.     (See  note  following  description  of  fig.  2h.) 
2c.  Small  dorsal  valve  associated  with  the  specimen  represented  by  figure  2.     U.  S.  Nat.  Mus.  Cat.  No.  51762v. 
2d.  Dorsal  valve,  the  type  specimen,  slightly  broadened  by  compression;  from  Locality  307,  Upper  Cam- 
brian, McLeod  Brook,  Cape  Breton,  Nova  Scotia.     University  of  Toronto,  Canada.     Drawn  from  one 

of  the  specimens  figured  by  Matthew  [1901,  PI.  V,  figs.  2a-b],  but  closer  identification  is  impossible. 
2e.  Dorsal  valve  associated  with  the  specimen  represented  by  figure  2,  slightly  broadened  by  compression. 

U.  S.  Nat.  Mus.  Cat.  No.  51762w. 
2f.  Dorsal  valve  associated  with  the  specimen  represented  by  figure  2,  more  or  less  distorted  by  compression  in 

the  shale.     U.  S.  Nat.  Mus.  Cat.  No.  51762x. 
2g.  Distorted  dorsal  valve  from  Locality  372,  Upper  Cambrian  shale  at  Upper  Lcitches  Creek,  Cape  Breton, 

Nova  Scotia.     U.  S.  Nat.  Mus.  Cat.  No.  .52449a. 
2h.  Dorsal  valve  associated  with  the  ventral  valve  represented  by  figures  2  and  2b.     U.  S.  Nat.  Mus.  Cat. 

No.  51762y.     Figures  2b  and  2h  preserve  the  original  convexity  and  outline  of  the  shell  more 

perfectly  than  those  compressed  in  the  fine  shales. 

Obolus  (Westonia)  ELt.A  (Hall  and  Whitfield)  (p.  455). 

(PI.  XLVir,  figs.  1,  la-p.) 

Figures  3  and  3a.  Associated  dorsal  valves  distorted  by  movement  in  shale,  one  being  broadened,  and  the  other 
elongated.     U.  S.  Nat.  Mus.  Cat.  Nos.  51684a  and  51684b,  respectively. 
3b  and  3c.  Dorsal  and  ventral  valves  compressed  and  distorted  in  fine  shale.     U.  S.  Nat.  >Ius.  Cat.   Nos. 
51684c  and  51684d,  respectively. 

The  figures  all  represent  specimens  from  Locality  3c,  Middle  Cambrian  shales  near  Ophir,  Utah,  and  are  intro- 
duced to  illustrate  the  forms  this  species  may  often  take  where  the  fine  shells  have  been  more  or  less  compressed  and 
stretched.     They  should  be  compared  with  the  prevailing  form  of  the  species  as  shown  on  Plate  XLVIL 

LiNGULELLA    (LiNGULEPIS)    EXIGCA    (Mattlll'W)     (p.    551). 

[PI.  XLHI,  figs.  1,  la-z.] 

Figure  4.  Group  of  young  shells  occurring  in  fine,  arenaceous  shale,  Locality  31,  Middle  Cambrian  on  McLean  Brook, 
1.5  miles  west  of  Marion  Bridge,  Cape  Breton,  Nova  Scotia,  in  which  the  adult  specimens  represented 
on  Plate  XLIII  occur.  U.  S.  Nat.  Mus.  Cat.  No.  34761s. 
4a.  Specimen  in  which  the  substance  of  the  shell  has  been  etched  by  acid  so  as  to  leave  in  relief  the  siliceous 
matter  filling  the  fractures  in  the  shell.  Locality  10s,  Middle  Cambruin  sandstone  on  McLean 
Brook,  near  Marion  Bridge,  Cape  Breton,  Nova  Scotia.  \J.  S.  Nat.  Mus.  Cat.  No.  5246Sa.  The 
original  specimen  is  12  mm.  in  length.  The  system  of  fractures  is  very  complicated  within  the  two 
main  lines  of  fracture  which  cross  each  other  obliquely,  forming  rhomboidal  spaces. 
IIG 


MONOGRAPH  LI     PL.  XXXIII 


U.  3.  GEOLOGICAL  SURVEY 


FRANCES  WIESER  DEL. 


MELIOTVPE    CO    eOSTOM 


PLATE    XXXIV. 


117 


PLATE  XXXIV. 
LiNGULELLA  coNCiNNA  Matthew  (p.  486). 

[I'l.  XXXIII,  figs.  2,  2a-h.) 

Figure  1.  This  ventral  valve  is  somewhat  doubtfully  referred  to  this  species.  The  specimen  from  which  the  figure 
was  drawn  occurs  in  Locality  310h,  Upper?  Cambrian  shales  in  the  Province  of  Skane,  Sweden,  and 
is  more  nearly  related  to  some  forms  of  Lingulella  concinna  than  to  other  species  from  the  Upper 
Cambrian  and  Lower  Ordovician.     U.  S.  Nat.  Mus.  Cat.  No.  14932a. 

la-h.  Ventral  valves  illustrating  variations  in  outline,  convexity,  etc.,  from  Locality  3h,  Ujiper  Cambrian 
shale  on  McNeil  Brook,  Cape  Breton,  Nova  Scotia.     U.  S.  Nat.  Mus.  Cat.  Nos.  517G2a-h,  re.spectively. 

li-q.  Dorsal  valves  associated  with  the  ventral  valves  represented  by  figures  la-h.  L'.  S.  Nat.Mua.  Cat.  Nos. 
51762i-q,  respectively. 

Ir.  Three  ventral  valves  and  fragments  of  a  dorsal  valve  associated  with  the  shells  represented  by  figures  la-q 
(X  2).     U.  S.  Nat.  Mus.  Cat.  No.  51762r. 

Obolus  septalis   (Walcott)   (p.  414). 

[I'l.  XXIII,  fie.  3d.] 

Figure  2.  Exterior  of  dorsal  valve.     Collection  of  Mr.  Byron  E.  Walker,  Toronto,  Canada. 

2a.  Cast  of  interior  of  dorsal  valve,  the  type  specimen.     V.  S.  Nat.  Mus.  Cat.  No.  51612a. 

The  specimens  are  both  from  Locality  14s,  Middle  Cambrian  Ogygopsis  zone  on  Mount  Stephen,  British  Columbia. 
Lingulella  (Lingulepis)  acuminata  (Conrad)   (p.  .545). 

[PI.  XL,  figs.  1,  la-s;  PI.  XLI,  figs.  1,  la-n;  and  PI.  XLII,  figs.  1,  la-o.] 

Figure  3.  Ventral  valve  with  the  apex  worn  off,  from  Locality  7z,  Upper  Cambrian  limestone  about  3  miles  southeast 

of  Emigrant  Pass,  Esmeralda  County,  Nevada.     IT.  S.  Nat.  Mus.  Cat.  No.  51884a. 
3a.  Ventral  valve  intermediate  in  form  between  specimens  represented  by  figures  3  and  3b,  from  Locality  7y, 

Upper  Cambrian  limestones  2.5  miles  southeast  of  Emigrant  Pass,  Esmeralda  County,  Nevada.     U.  S. 

Nat.  Mus.  Cat.  No.  56967a. 
3b.  Broad  form  of  ventral  valve  with  apex  broken  off,  from  Locality  7x,  L'pper  Cambrian  limestones  2.5  milca 

southeast  of  Emigrant  Pass,  Esmeralda  County,  Nevada.     L'.  S.  Nat.  Mus.  Cat.  No.  56967b. 
3c  and  3d.  Dorsal  valves  associated  with  the  shell  represented  by  figure  3.     U.  S.  Nat.  Mus.  Cat.  Nos.  51884b 

and  51884c,  respectively. 
3e.  A  small,  slender  ventral  valve  associated  with  the  shell  represented  by  figure  3.     U.  S.  Nat.  Mus.  Cat.  No. 

51884d. 
118 


U,  S.  GEOLOGICAL  SURVEY 


MONOGRAPH   LI     PL.  XXXIV 


^V.! 


FflANCES  WIESER  OEL. 


MELtOTVPE   CO    BOSTOM 


PLATE   XXXA 


T 


119 


PLATE  XXXV. 

a.  Central  lateral  space  of  area.  p.  Pedicle  groove, 

a'.  Outer  lateral  space  of  area.  s.  Median  septum. 

f.  Flexure  line  of  area.  v.  Visceral  cavity. 

h.  Central  muscle  scar.  vs.  Main  vascular  sinus, 
j.  Anterior  lateral  muscle  scar. 

LiNGtXELLA  coLLiciA  (Matthew)  (p.  486). 

Figure  1.  Exterior  of  an  imperfect  ventral  valve,  the  type  gpecimen.     University  of  Toronto,  Canada. 

la.  Partly   exfoliated  ventral   valve,   showing  ^-isceral  area  and  vascular  sinuses.     University  of  Toronto, 
Canada. 

lb.  Crushed  and  broken  cast  of  the  interior  of  a  ventral  valve.     University  oi  Toronto,  Canada. 
The  specimens  represented  by  figures  1,  la-b  are  from  Locality  13n',  Middle  Cambrian  sandy  shales  of  Division 
E3e,  Dugald  Brook,  Cape  Breton,  Nova  Scotia.     The  figures  are  drawn  from  three  of  the  specimens  illustrated  by  Mat- 
thew [1899b,  PI.  I,  figs.  3a-e],  but  closer  identification  is  impossible. 

Figure  Ic.  Exterior  of  a  dorsal  \alve  broadened  and  distorted  by  compression.     Locality  13m,  Middle  Cambrian 

sandstones  of  Division  E3f,  Gillis  Brook,  Cape  Breton,  Nova  Scotia.    U.  S.  Nat.  Mus.  Cat.  No.  51772a. 
Id.  Imperfect   cast  of  interior  of   a  dorsal  valve  from  Locality  13n',  Middle  Cambrian   sandy  shales  of 

Division  E3e,  Dugald  Brook,  Cape  Breton,  Nova  Scotia.     U.  S.  Nat.  Mus.  Cat.  No.  524.53a. 
le.  Imperfect  cast  of  interior  of  a  flattened  dorsal  valve  from  Locality  lOp,  Middle  Cambrian  sandy  shales 

of  Division  E2b,  Dugald  Brook,  Cape  Breton,  Nova  Scotia.     U.  S.  Nat.  Mus.  Cat.  No.  35294a. 
If.  Cast  of  the  interior  of  a  ventral  valve  associated  with  the  shell  represented  in  figure  le.    U.  S.  Nat.  Mus. 

Cat.  No.  3.5294b. 
2.  Cast  of  interior  of  ventral  valve  from  Locality  ISm,  Middle  Cambrian  sandstones  of  Division  E3f,  Gillis 

Brook,  Cape  Breton,  Nova  Scotia,  showing  area  and  position  of  vascular  sinuses.     U.  S.  Nat.  Mus. 

Cat.  No.  57084a. 
2a.  Exterior  of  a  slightly  distorted  ventral  valve  associated  with  the  specimen  represented  by  figure  2.     U.  S. 

Nat.  Mus.  Cat.  No.  57084b. 
2b.  Broad  ventral  valve,  doubtfully  referred  to  this  species,  from  Locality  lOp,  Middle  Cambrian  sandy  shales 

of  Di\dsion  E2b,  Dugald  Brook,  Cape  Breton,  Nova  Scotia.     U.  S.  Nat.  Mus.  Cat.  No.  57083a. 
2c.  Dorsal  valve  associated  with  the  specimen  represented  by  figure  2a.     U.  S.  Nat.  Mus.  Cat.  No.  57084c. 
2d.  Interior  of  a  dorsal  valve  associated  with  the  specimen  represented  by  figure  2a,  showing  a  strong  median 

ridge  and  the  position  of  the  central  muscle  scars.     U.  S.  Nat.  Mus.  Cat.  No.  57084d. 

Figures  2,  2a-d  represent  forms  corresponding  to  those  referred  by  Matthew  [1903,  pp.  114-115]  to  Leptobolus 
collicia  collis. 

LiNGULELLA    CANIA    (Walcott)    (p.  484). 

Figures  3  and  3b.  Casts  of  the  interior  of  ventral  valves  from  Locality  3i,  Middle  Cambrian  sandy  shale  on  McLean 
Brook,  1.5  miles  west  of  Marion  Bridge,  Cape  Breton,  Nova  Scotia.     U.  S.  Nat.  Mus.  Cat.  Nos.  52451a 
and  52451c,  respectively.     Figure  3  represents  the  type  specimen. 
3a.  Partly  exfoliated  ventral  valve  associated  with  the  shells  represented  in  figures  3  and  3b.     U.  S.  Nat. 

Mus.  Cat.  No.  •52451b. 
3c.  Exterior  of  dorsal  valve  from  Locality  IDs,  Middle  Cambrian  sandstone  on  McLean  Brook,  near  Marion 
Bridge,  Cape  Breton,  Nova  Scotia.     U.  S.  Nat.  Mus.  Cat.  No.  35295a. 
•  3d.  Cast  of  interior  of  dorsal  valve  associated  with  the  specimens  represented  by  figures  3  and  3b.     U.  S.  Nat. 
ilus.  Cat.  No.  52451d. 

LiNGULELLA  FERRUGixEA  Salter  (p.  496). 

[PI.  XXIX,  tigs.  1,  la-w,  2,  2a-f:  PI.  XXX,  fig.  1;  and  PI.  XXXI,  figs.  3,  3a-c.l 

FiGURE.s  4  and  4a.  Partly  exfoliated  ventral  valves,  showing  cast  of  the  area  and  pedicle  ftirrow,  from  Locality  3h, 
Middle  Cambrian  arenaceous  shales,  McNeil  Brook,  1.5  miles  east  of  Marion  Bridge,  Cape  Breton, 
Nova  Scotia.     U.  S.  Nat.  Mus.  Cat.  Nos.  517.58a  and  517.5.Sb,  respectively. 
4b.  Dorsal  valve  associated  with  the  ventral  valves  represented  by  figures  4  and  4a.    U.  S.  Nat.  Mus.  Cat. 
No.  517.58c. 
120 


U.  S.  GEOLOGICAL  SURVEY 


MONOGRAPH   LI     PL.  XXXV 


FRANCES  WIESER  DEL. 


neuiOTvpe  ro  bcston 


PLATE  XXXV.  121 

LiNGULELLA    ATAVA  (Miltthow)    (p.  479). 

Figure  5.  Exterior  of  ventral  valve  from  Locality  13n',  Middle  Cambrian  sandstones  of  Division  E3e,  Dugald  Brook, 

Cape  Breton,  Nova  Scotia.    Type  specimen,  figured  by  Matthew  [1899b,  PI.  II,  fig.  la]  as  Leplobolus 

atavus. 
5a  and  5b.  Partly  exfoliated  ventral  valves,  showing  area,  pedicle  furrow,  and  outline  of  visceral  cavity. 

Locality  lOp,  Middle  Cambrian  sandstones  of  Division  E2b,  Dugald  Brook,  Cape  Breton,  Nova  Scotia. 

U.  S.  Nat.  Mus.  Cat.  Nos.  35293a  and  35293b,  respectively. 
5c.  Dorsal  valve  associated  with  the  specimens  represented  by  figure  5.      University  of  Toronto,  Canada. 

Specimen  figured  by  Matthew  [1899b,  PI.  II,  fig.  Id]  as  Leplobolus  alarus. 
5d.  Cast  of  interior  of  dorsal  valve,  showing  outline  of  visceral  area,  position  of  anterolateral  muscle  scars, 

vascular  sinuses,  and  area.     Locality  13n',  Middle  Cambrian  sandy  shales  of  Division  E3e,  Dugald 

Brook,  Cape  Breton,  Nova  Scotia,    "u.  S.  Nat.  Mus.  Cat.  No.  524.50a. 
5e.  Dorsal  valve.    The  specimen  can  not  now  be  located.     It  was  in  the  collections  of  the  United  States 

National  Museum,  but  the  locality  is  unknown. 
5f,  5g,  and  5h.  Casts  of  laterally  compressed  dorsal  valves  associated  with  the  ventral  valves  represented  by 

figures  5a  and  5b.     U.  S.  Nat.  Mus.  Cat.  Nos.  35293c,  35293d,  and  35293e,  respectively. 

LiNGULELLA  FLUMENis  (Matthew)  (p.  500). 

Figure  6.  Exterior  of  imperfect  ventral  valve.     University  of  Toronto,  Canada.     Type  specimen,  figured  by  Matthew 

[1903,  PI.  XI,  fig.  7a]  as  Leplobolus  flumenis. 
Ga.  Interior  of  dorsal  valve.     University  of  Toronto,  Canada.     Specimen  figured  by  Matthew  [1903,  PI.  XI, 

fig.  7b]  as  Leplobolus  flumenis. 
6b.  Cast  of  interior  of  dorsal  valve.     University  of  Toronto,  Canada.     Specimen  figured  by  Matthew  [1903, 

PI.  XI,  fig.  7e]  as  Leplobolus  flumenis. 

The  specimens  represented  are  all  from  Locality  325a,  Middle  Cambrian  shales  of  Division  C2c  on  McNeil  Brook, 
Cape  Breton,  Nova  Scotia. 

LiNGULELLA  TORRENTis  (Matthew)  (p.  5.35). 

Figure  7.  Ventral  valve  from  Locality  344f ,  Middle  Cambrian  shales  of  Matthew's  Coldbrook  gioup,  Dugald  Brook,  Cape 
Breton,  Nova  Scotia.  University  of  Toronto,  Canada.  Type  specimen,  figured  by  Matthew  [1903, 
PI.  VI,  lig.  1]  as  Leplobolus  lorrentis. 

LiNGULELLA  ATAVA  INSULA  (Matthew)  (p.  4S0J. 

Figures  8  and  Sa.  Ventral  and  dorsal  valves  from  Locality  307d,  Middle  Cambrian  sandy  limestone  ot  Division  E2a?, 
at  Youngs  Point  near  George  River  Station,  Cape  Breton,  Nova  Scotia.  Universitj'  of  Toronto,  Canada. 
Specimens  figured  by  Matthew  [1903,  PI.  VI,  figs.  4a  and  lb]  as  Leplobolus  alavus  insutiv.  Figure  8 
represepts  the  type  specimen. 

LiNGULELLA    ORA    (Walcott)    (p.  522). 

Figure  9.  Exterior  of  a  broken  \entral  valve,  the  type  specimen,  from  Locality  9p,  Upper  Cambrian  limestone,  15 

miles  northwest  of  Fort  Sill,  Comanche  County,  Oklahoma.     U.  S.  Nat.  Mus.  Cat.  No.  51794a. 
9a  and  9a'.  Top  and  side  \'iew3  of  a  partly  exfoliated  ventral  valve  which  illustrates  the  thickness  of  the 

shell,  from  Locality  9q,  Upper  Cambrian  limestone,  15  miles  northwest  of  Fort  Sill,  (_'omanche  County, 

Oklahoma.     U.  S.  Nat.  Mus.  Cat.  No.  51795a. 
9b  and  9b'.  Top  and  side  views  of  a  ventral  valve  associated  with  the  shell  represented  in  figure  9,  showing 

the  outer  surface  of  one  of  the  inner  layers  of  the  shell.     U.  S.  Nat.  Mus.  Cat.  No.  51794b. 
9c  and  9c'.  Top  and  side  views  of  an  elongate  dorsal  valve  as.sociated  with  the  shell  represented  in  figure  9. 

U.  S.  Nat.  Mus.  Cat.  No.  51794c. 
9d.  Short  broad  form  of  dorsal  valve  associated  with  the  shell  represented  in  figure  9.    U.  S.  Nat.  Mus.  Cat. 

No.  51794d. 


PLATE    XXXVI. 


123 


PLATE  XXXVI. 

c.  Trapezoidal  area,  including  central,  middle              p.  Pedicle  groove, 

lateral,  and  outside  lateral  muscle  scars.  .s.  Median  scjitum. 

g.  Umbonal  muscle  scar.  v.  Visceral  cavity, 

h.  Central  muscle  scar.  vs.  Main  vascular  sinus, 

i.  Transmedian  muscle  scar.  ivs.  Lateral  branches  of  vascular  system, 

j.  -\nterior  lateral  muscle  scar.  pvs.  Peripheral  branches  of  vascular  system. 

k.  Middle  lateral  muscle  scar.  x.  Ilcart-shapeil  cavity. 
1.  Outside  lateral  muscle  scar. 

Obolus  selwyni  (^^atthe\v)  (p.  413). 

[PI.  .K.KXVII.  figs.  1,  la-f.] 

Figure  1.  luterior  of  a  dorsal  valve,  showing  a  portion  of  the  visceral  area  and  adjoining  parts;  al.so  the  striation  of 

one  of  the  inner  layers  of  the  shell.     University  of  Toronto,  Canada.     Redrawn  (with  fig.  If)  from  the 

specimens  on  which  Matthew  [1903]  based  the  diagrammatic  figures  in  the  left-hand  figure  on  page 

117  and  figures  la  and  Ic  of  Plate  VII  of  his  paper, 
la.  Exfoliated  ventral  valve,  showing  the  visceral  area  and  adjoining  portions  of  the  interior  of  the  shell. 

University  of  Toronto,  Canada, 
lb.  Side  outline  of  specimen  represented  by  figure  la. 
Ic.  Interior  of  a  ventral  valve,  longitudinally  compressed,  which  emphasizes  the  main  vascular  sinuses  and 

the  lateral  branches  of  the  vascular  system.     University  of  Toronto,  Canada.     Redrawn  (mth  fig.  I) 

from  the  specimens  on  which  Matthew  [1903]  based  the  diagrammatic  figures  in  the  left-hand  figure 

on  page  117  and  figures  la  and  Ic  of  Plate  VII  of  his  paper. 
Id.  Interior  of  a  dorsal  valve,  shomng  portions  of  the  vascular  system.     University  of  Toronto,  Canada. 
le,  If,  and  Ig.  Interior  of  dorsal  valves,  showing  variation  in  position  of  the  central  and  anterior  lateral  muscle 

scars.     University  of  Toronto,  Canada. 
Ih.  Dorsal  valve  longitudinally  compressed,  giving  it  a  very  broad  form.     This  may  he  compared  with  figures 

Ic  and  If  of  Plate  XXXVII.     University  of  Toronto,  Canada. 
2.  Cast  of  interior  of  a  ventral  valve,  broadened  by  compression.     University  of  Toronto,  Canada.     Specimen 

figured  by  Matthew  [1902c,  PI.  I,  fig.  4b]  as  Oholus  iequiputeis. 
2a.  Cast  of  interior  of  a  dorsal  valve.     University  of  Toronto,  Canada.     Specimen  figured  by  Matthew  [1902c, 

PI.  I,  fig.  4d]  as  Obolus  a:quiputeis. 
2b.  Cast  of  the  interior  of  a  dorsal  valve.     University  of  Toronto,  Canada. 

The  specimens  represented  are  all  from  Locality  307d,  Middle  Cambrian  sandy  limestone  of  Division  E2a?  on  Youngs 

Point,  near  George  River  Station,  Cape  Breton,  Nova  Scotia. 

LiNGULELL.v  t'pi.s  (Walcott)    (p.  .538). 

Figures  3  and  3'.  Top  and  side  views  of  partly  exfoliated  ventral  valve,  the  type  specimen,  from  Locality  14i,  Upper 
Cambrian  limestone  1  mile  west  of  Cherokee,  San  Saba  County,  Texas.     U.  S.  Nat.  Mus.  Cat.  JIo. 
51804a. 
3a.  Fragmentary  dorsal  valve  associated  with  the  ventral  \al\-e  represented  by  figure  3.     U.  S.  Nat.  Mus. 
Cat.  No.  51S04b. 

LlXGUI>KI.LA    BELL.V    (Walcott)     fp.  4.S1). 

|1>1.  XIX,  figs.  2.  2a-(i.] 

Figure  4.  Slab  of  arenaceous  shale  with  numerous  well-preserved  shells  from  Locality  H4b,  Lower  Ordnvician  sand- 
stone 1  mile  north  of  Lance  Cove,  Great  Belle  Island,  Conception  IJay,  Newfoundland.     L'.  S.  Mat. 
Mus.  Cat.  No.  2730Sn. 
124 


U.  S.   GEOLOGICAL  SURVEY 


MONOGRAPH   LI     PL.  XXXVI 


'  <  .''X^J  __.ji'^ 


t^RANCES  W>ESER  DEL. 


BLioTVPC  :c  eo 


PLATE    XXXVII. 


125 


PLATE  XXXVII. 

c.  Trapezoidal  area,  including  central,  p.  Pedicle  groove. 

middle  lateral,  and  outside  lateral  ps.  Parietal  band. 

muscle  scars.  s.  Median  septum. 

g.  TJmbonal  muscle  scar.  v.  Visceral  cavity. 

h.  Central  muscle  scar.  vs.  Main  va.scular  sinus, 

i.  Transmedian  muscle  scar.  ivs.  Lateral  branches  of  the  vascular  sj'.stein. 

j.  .\nterior  lat;'ral  muscle  scar.  x.  Heart-shaped  cavity. 
1.  Outside  lateral  muscle  scar. 

Obolus  selwyni  (Mattliew)    (p.  41.3). 

[PI.  XXXVI,  figs.  1.  la-h,  2,  L'a-b.] 

Figure  1.  Exterior  of  a  distorted  ventral  valvo.  University  of  Toronto,  Canada.  Possibly  one  of  the  specimens  used 
by  Matthew  in  preparing  the  diagrammatic  figures  mentioned  under  figure  Ic. 

la.  Cast  of  an  interior  of  a  ventral  valve.     University  of  Toronto,  Canada. 

lb.  Cast  of  an  interior  of  a  ventral  valve  that  has  been  compressed  laterally.  Univetsity  of  Toronto,  Canada. 
Possibly  one  of  the  specimens  used  by  Matthew  in  preparing  the  diagrammatic  figures  mentioned 
under  figure  Ic. 

Ic.  Cast  of  an  interior  of  a  dorsal  valve.  University  of  Toronto,  Canada.  Redrawn  from  the  specimen  upon 
which  Matthew  [1903]  based  the  diagrammatic  figures  in  the  right-hand  figure  on  page  117  and  in 
figure  lb  of  Plate  VII  of  his  paper.     It  may  be  taken  as  the  type. 

Id.  Finely  preserved  interior  of  a  ventral  valve.  University  of  Toronto,  Canada.  Possibly  one  of  the  speci- 
mens used  by  Matthew  in  preparing  th  e  diagrammatic  figures  mentioned  under  figure  Ic. 

le.  Interior  of  the  posterior  portion  of  a  dorsal  valve.     University  of  Toronto,  Canada. 

If.  Cast  of  an  interior  of  a  dorsal  valve.  University  of  Toronto,  Canada.  Possibly  one  of  the  specimens  used 
by  Matthew  in  preparing  the  diagrammatic  figures  mentioned  under  figure  le. 

The  specimens  represented  are  all  from  Locality  307d,  Middle  Cambrian  sandy  limestone  of  Divi.-ion  E2a?  on 
Youngs  Point,  near  George  River  Station,  Cape  Breton,  Nova  Scotia. 

LiNGULELLA   (LiNGULEPis)  STARRi   (Matthew)    (p.  5.59). 

Figure  2.  Poorly  preserved  ventral  valve.     University  of  Toronto,  Canada. 

2a.  Dorsal  valve  preserving  a  portion  of  the  shell.     University  of  Toronto,  Canada. 
2b.  Cast  of  a  portion  nf  the  interior  of  a  ventral  valve.     T'niversity  of  Toronto,  Canada. 

The  specimens  represented  are  all  from  Lmalit  y  308c,  Upp<  r  <  'ambrian  shales  of  Matthew's  Johannian  at  St.  John, 
New  Brunswick.  According  to  Matthew  the  type  .specimens  have  been  <ilh(  r  miflaid  (<i  lost.  -Ml  the  fifrurr.s  are 
drawn  from  new  material  collected  by  him  at  the  type  locality. 

LixGULELLA  MixoR   (Matthtnv)    (p.  .510). 

Figure  3.  Cast  of  the  exterior  id' a  ventral  valve  slightly  compres.sed  and  distorted  in  the  .shale.     University  of  Toronto, 

Canada.     Type  specimen,  figured  by  Matthew  [1892,  PI.  XII,  fig.  .5a]  as  LingnleUa  starri  minor. 
3a.  Dorsal  valve  from  which  nearly  all  of  the  shell  is  exfoliated.     University  of  Toronto,  Canada.     Specimen 

figured  by  Matthew  [1892,  PI.  XII,  fig.  5b]  as  Lingulella  starri  viinor. 
3b.  Enlargement  of  the  outer  surface  of  the  shell.     University  of  Toronto,  Canada. 
3c.  Ventral  valve  from  siliceous  -shale.     U.  S.  Nat.  Mus.  Cat.  No.  517(i.5a. 
3d  and  3e.  Small  ventral  and  dorsal  valves  from  a  fine  arenaceous  shale.     U.  S.  Nat.  Mus.  Cat.  Xos.  51765b 

and  51765c,  respectively. 
3f  and  3g.  Small  broad  form  of  ventral  and  dorsal  valves  associated  with  narrower  forms  represented  by  figures 

3d  and  3e.     V.  S.  Nat.  Mus.  Cat.  Nos.  517G5d  and  5I7G.5e,  respectively. 

The  specimens  are  all  frum  Locality  2x,  Upper  Cambrian  sandstones  on  Long  Island,  Kennebecasis  Bay,  St.  John 
County,  New  Brunswick. 
126 


U.  S.  GEOLOGICAL  SURVEY 


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t^RANCeS  WtESER  OEl. 


MELIOTVPC    CO    eCSTOH 


PLATE  XXXVII.  127 

LiNGULELLA    ROTUNDA    (Mattliew)     (]).  530, 

Figure  3h.  Exterior  of  a  small  ventral  valve.     U.  S.  Nat.  Mus.  Cat.  No.  51770a. 
3i.  Cast  of  interior  of  ventral  valve.     U.  S.  Nat.  Mus.  Cat.  No.  51770b. 
3j  and  3k.  Casts  of  interior  of  dorsal  valves.     U.  S.  Nat.  Mus.  Cat.  Nos.  51770c  and  51770d. 

The  specimens  represented  are  all  from  Locality  3i,  Middle  Cambrian  sandy  shale  on  McLean  Brook,  1,5  miles  west 
of  Marion  Bridge,  Cape  Breton,  Nova  Scotia. 

LiNGULELLA   (LiNGXJLEPis)  ROBERTi   (Matthew)    (p.  557). 

Figure  4.  Ventral  valve  preserving  a  portion  of  the  outer  surface.     University  of  Toronto,  Canada. 

4a.  Cast  of  the  interior  of  a  ventral  valve,  the  type  specimen.     University  of  Toronto,  Canada.     (See  note 

following  4d.) 
4b.  Cast  of  the  interior  of  a  dorsal  valve,  preser\-ing  outline  and  convexity  of  val\-e  and  impressions  of  muscle 

scars.     University  of  Toronto,  Canada.     (See  note  following  4d.) 
4c.  Enlargement  of  a  portion  of  the  outer  surface  of  the  antericir  portion  of  a  dorsal  valve.     University  of 

Toronto,  Canada. 
4d.  Dorsal  valve  distorted  by  compre.ssion.     University  of  Toronto,  Canada. 

The  figures  are  all  drawn  from  specimens  in  Matthew's  type  material.  It  is  possible  that  the  specimens  represented 
by  figures  4a  and  4b  are  the  ones  figured  by  Matthew  [1895b,  PI.  I,  figs.  2a  and  2b,  respectively],  but  closer  identification 
is  impossible.  The  specimens  represented  are  all  from  Locality  307d,  Jliddle  Cambrian  sandy  limestone  of  Division 
E2a?  at  Youngs  Point,  near  George  River  Station,  Cape  Breton,  Nova  Scotia. 


PLATE    XXXVIII. 


62667°— VOL  51,  PT  2— 12 9  129 


PLATE  XXXVIII. 

a.  Central  lateral  space  of  area.  s.  Median  septum, 

a'.  Outer  lateral  space  of  area.  v.  Visceral  cavity, 

f.  Fle-xure  line  of  area.  vs.  Main  vascular  sinus, 

h.  Central  muscle  .scar.  ivs.  Lateral  branches  of  the  vascular  system. 

,                           j.  Transmedian  muscle  scar.  pvs.  Periplieral  branches  of  the  vascular  system. 

p.  Pedicle  groove.  x.  Heart-shaped  cavity. 

LiNGULELLA    MARTINENSIS    MattlieW   (p.  51 S^. 

Figure  1.  E.xterior  of  an  unusually  well-prcsorved  ventral  valve.     University  of  Toronto,  Canada,     Drawn  from 
a  specimen  in  Matthew's  type  and  fi},'ured  material,  but  closer  identification  is  impossible, 
la.  Cast  of  the  interior  of  a  ventral  valve.     University  of  Toronto,  Canada.     Type  specimen  figured   by 

Matthew  [1895a,  PI.  II,  fig.  6d]. 
lb.  Interior  of  a  ventral  valve  from  which  nearly  all  of  the  inner  layers  of  the  shell  have  been  exfoliated. 
University  of  Toronto,  Canada.     Drawn  from  a  specimen  in  Matthew's  type  and  figured  material,  but 
closer  identification  is  impossible. 
Ic.  Interior  of  a  dorsal  valve.     University  of  Toronto,  Canada.     Drawn  from  a  specimen  in  Matthew's  typeand 

figured  material,  but  closer  identification  is  impossible. 
Id.  Cast  of  the  interior  of  a  dorsal  valve.     University  of  Toronto,  Canada.     Specimen  figured  by  Matthew 

[189.5a,  PI.  II,  fig.  6b]. 
le.  Enlargement  of  the  area  of  the  specimen  represented  by  figure  id. 
The  specimens  represented  by  figures  1,  la-e  are  from  Locality  2f,  Middle  Cambrian  sandstones  of  Division  Ibl, 
on  Ilanford  Brook,  St.  John  County,  New  Brunswick. 

Figures  If  and  Ig.  Ventral  and  dorsal  valves  which  occur  in  the  collection  of  the  University  of  Toronto,  Canada, 
labeled  by  Matthew  as  Linguldla  dciwsoni  from  Division  Ic  of  the  St.  John  slate.  They  appear 
to  be  more  nearly  related  to  LinguleUa  martinensis.  They  may  or  may  not  be  the  specimena 
illustrated  by  Matthew  [1880,  PI.  V,  figs.  9,  9a-c]. 

LiNGULELLA    GRANDIS    (Mattliew)    (p.  50"2). 

Figure  2.  Partly  exfoliated  dorsal  valve.     University  of  Toronto,  Canada. 

2a.  Cast  of  the  interior  of  the  posterior  portion  of  a  ventral  valve.     University  of  Toronto,  Canada. 
Figures  2  and  2a  (with  2c  and  2d )  are  drawn  from  specimens  in  Matthew's  type  material  of  LinguleUa  f  cuneata,  but 
it  is  impossible  to  tell  which  of  these  he  figured  [1894,  PL  XA'I,  figs.  .5a-b]. 

Figure  2b.  Slightly  imperfect  cast  showing  the  greater  part  of   the  interior  of  a   ventral  valve.     University  of 
Toronto,  Canada.     Type  specimen,  figured  by  Matthew  [1894,  PL  XVI,  fig.  7a]  as  Leptobolus  grandis. 
2c.  Cast  of  the  interior  of  a  ventral  valve.     University  of  Toronto,  Canada. 
2d.  Cast  of  the  interior  of  a  dorsal  valve.     University  of  Toronto,  Canada. 
Figures  2c  and  2d  (with  2  and  2a)  are  drawn  from  specimens  in  Matthew's  type  material  of  LingukUa  f  cuneata,  but 
it  is  impossible  to  tell  which  of  these  he  figured  [1894,  PL  XVI,  figs.  5a-b]. 

Figure  2e.  Posterior  portion  of  a  dorsal  valve,  showing  cast  of  the  area.     L'niversity  of  Toronto,  Canada.     Labeled 
by  Matthew  as  Leptobolus  grandis. 
2f.  Part  of  the  interior  of  a  dorsal  valve.     University  of  Toronto,  Canada.     Specimen  figured   by  Matthew 
[1894,  PL  XVI,  fig.  7b]  as  Leptobolus  grandis. 
The  specimens  represented  by  figures  2,  2a-f  are  all  from  Locality  30Is,  Lower  Ordovician  sandstone  at  McAphee's 
Comer,  Hardingville,  St.  John  County,  New  Brunswick. 

Obolus  belli   (Billintrs)  (p.  386). 

Figures  3 and  3a.  Ventral  valves  from  Locality  319n,  Ordovician,  on  the  island  of  Montreal.  Canada.     Geol.  Survey 
Canada.     Redrawn  from  the  specimens  figured  by  Billings  [18.59,  pp.  431-432,  figs.  7  and  8],  but  closer 
identification  is  impossible.     Figure  3  may  be  taken  as  the  type. 
3b.  Dorsal  valve  associated  with  the  specimens  represented  by  figures  3  and  3a.     Geol.  Survey  Canada. 

LiNGULELLA    WELLERI   (Walcott)    (p.  539). 

Figure  4.  Compressed  and  somewhat  crushed  ventral  valve,  the  type  specimen,  showing  only  the  general  outline 
and  the  outer  surface.     V.  S.  Nat.  Mus.  Cat.  No.  35292a. 
4a.  Apex  and  posterior  portion  of  the  ventral  valve,  preserving  the  convexity.     U.  S.  Nat.  Mus.  Cat.  No. 

35292b. 
4b.  A  compressed  dorsal  valve.     U.  S.  Nal.  Mu.«.  <'at.  No.  35292c. 
The  specimens  represented  are  all  from  Locality  lie,  Upper  Cambrian  sandstone,  O'Donnell  and  McManniman's 
quarry,  Newton,  New  Jersey. 
130 


U.  S.  GEOLOGICAL  SURVEY 


MONOGRAPH   LI     PL.  XXXVIII 


/ 


J^^<. 


Z" 


HELIOTYPE  CO..  BOSTON 


PLATE   XXXIX. 


131 


PLATE  XXXIX. 


a.  Central  lateral  space  of  area, 

a'.  Outer  lateral  space  of  area. 

f.  Flexure  line  of  area, 

h.  Central  muscle  scar, 

i.  Transmedian  muscle  scar, 

j.  Anterior  lateral  muscle  scar. 


1.  Outside  lateral  and  middle  lateral  muscle 

scars  on  dorsal  valve, 
p.  Pedicle  groove, 
s.  Median  septum. 
V.  Visceral  cavity, 
vs.  Main  vascular  sinus. 


LiNGULELLA   WANNiECKi  RedUch  (p.  538). 

Figure  1.  Elongate  form  of  the  ventral  valve.     U.  S.  Nat.  Mils.  Vat.  No.  51744o. 

la,  lb,  and  Ic.  Short,  broad,  subtriangular  forms  of  the  ventral  valve.     U.  S.  Nat.  Mus.  Cat.  Nos.  51744a, 

5i744b,  and  51744(",  respectively. 
Id.  Cast  of  the  interior  of  a  ventral  valve,  showing  the  area,  visceral  area,  and  \asciilar  sinuses.     U.  S.  Nat, 

Mus.  Cat.  No.  51744d. 
le.  Imperfect  interior  of  a  ventral  valve.     U.  S.  Nat.  Mus.  Cat.  No.  51744e. 
If.  Dorsal  valve  in  position  against  the  ventral  valve,  showing  the  area  of  the  ventral  valve.     U.  S.  Nat.  Mus. 

Cat.  No.  51744f. 
Ig,  Ih,  and  li.  Exteriors  of  dorsal  valves,  varying  somewhat  in  outline.     U.  S.  Nat.  Mus.  Cat.  Nos.  51744g, 

51744h,  and  51744i,  respectively. 
Ij  and  Ik.  Interiors  of  imperfect  dorsal  valves.     U.  S.  Nat.  Mus.  Cat.  Nos.  51744J  and  51744k,  respectively. 
1 1.  Interior  of  a  remarkably  well  preserved  dorsal  valve.     U.  S.  Nat.  Mus.  Cat.  No.  51744  1. 
Im.  Cast  of  the  interior  of  a  dorsal  valve.     U.  S.  Nat.  Mus.  Cat.  No.  51744m. 
In.  Interior  of  a  dorsal  valve,  showing  anterior  lateral  scars  and  narrow  ridges  in  the  position  of  the  main 

vascular  sinuses.     U.  S.  Nat.  Mus.  Cat.  No.  51744n. 

The  specimens  represented  are  all  from  Locality  15r,  Middle  Cambrian  argillaceous  shale  at  Khussak,  Salt  Range, 
India. 

LiNGULELLA  FiiCiisi  ReclHch  (p.  502). 

FiGUKE  2.  Narrow  elongate  form  which  may  be  compared  with  figure  3.     U.  S.  Nat.  Mus.  Cat.  No.  51746a. 
2a.  Cast  of  a  very  small  dorsal  valve.     U.  S.  Nat.  Mus.  Cat.  No.  51746b. 

2b  and  2c.  Dorsal  valves  referred  to  this  species.     U.  S.  Nat.  Mus.  Cat.  Nos.  51746c  and  51746d,  respectively. 
3.  Ventral  valve,  the  type  specimen.     Copied  from  Redlich  [1899,  PI.  I,  fig.  10c]. 

The  specimens  represented  are  all  from  Locality  15r,  Middle  Cambrian  argillaceous  shale  at  Khussak,  Salt  Range, 
India. 


LiNGULELLA  issE  (Walcott)  (p.  509). 

[Text  figs.  4:iA-F,  p.  5I0.I 

Figures  4  and  4a.  Narrow  and  broad  forms  of  ventral  valves,  with  e.xterior  shell  partly  exfoliated.     U.  S.  Nat.  Mus. 
Cat.  Nos.  51808a  and  51808b,  respectively.     Figure  4a  represents  the  type  specimen. 
4a'.  Side  outline  of  specimen  represented  by  figure  4a. 
4b  and  4b'.  Exfoliated  dorsal  valve  and  side  outline.     U.  S.  Nat.  Mus.  Cat.  No.  51808c. 

The  specimens  represented  are  all  from  Localil>'  15d,  ITpper  Cambrian  limestone  near  Cave  Spring,  Fish  Spring 
Range,  Utah. 

Obolits  mcconnelli  pelia.s  (Walcott)  (p.  398). 

[PI.  XXIII,  figs.  Sb-c.] 

Figure  5.  Ventral  valve  with  outer  layer  of  shell  exfoliated,  from  Locality  15p,  Middle  Cambrian  limestones  near  the 
north  end  of  the  Fish  Spring  Range,  Utah.     U.  S.  Nat.  Mus.  Cat.  No.  51597a. 
5a  and  5b.  Partly  exfoliated  dorsal   valves  as.sociated  with   the  specimen  repre.senled  by  figure  6.     U.  S. 

Nat.  Mus.  Cat.  Nos.  51597b  and  51597c,  respectively. 
5c.  A  dorsal  valve  doubtfully  referred  to  this  species,  from  Locality  7s,  Upper  Cambrian  shale  4  miles  south- 
southeast  of  Emigrant  Peak,  Silver  Peak  quadrangle,  Nevada.     U.  S.  Nat.  Mus.  Cat.  No.  51593a. 
132 


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MELIOTYPE  CO..  BOSTON, 


PLATE  XXXIX.  133 

LiNGULELLA    QUADRILATERALIS   (Walcott)    (p.  528). 

Figure  G.  Ventral  valve  with  outer  layer  of  shell  exfoliated,  the  type  Bpecimen,  from  I-ocality  91,  Middle  <  aiiilirian 
shales  at  Cedar  Bluff,  Cherokee  County,  Alabama.     U.  S.  Nat.  Mus.  Cat.  No.  51777a. 
Ga.  I>ursal  valve  and  side  outline  of  united  valves,  associated  with  the  specimen  represented  by  figure  6. 
U.  S.  Nat.  Mus.  Cat.  No.  51777b. 

Obolus  chinensis  (Walcott)  (p.  387). 

Figure  7.  Partly  exfoliated  ventral  valve,  the  type  specimen.     U.  S.  Nat.  Mus.  Cat.  No.  52532a. 

7a.  Interior  of  a  ventral  valve.     U.  S.  Nat.  Mus.  Cat.  No.  52532b.     Another  specimen  (Cat.  No.  52532c)  was- 

used  to  restore  certain  parts  of  this  drawing. 
7b.  Exfoliated  dorsal  valve,  showing  visceral  area.     U.  S.  Nat.  Mus.  Cat.  No.  52532d. 

The  specimens  represented  are  all  from  Locality  C62,  Middle  Cambrian  limestones  2.5  miles  south  of  Yenchuang, 
Sintai  district.  Shantung,  China. 

LiNGULELLA    DAMESI    (Walc'Ott)    (]).  489). « 

Figure  8.  Top  and  side  view  of  a  partly  exfoliated  ventral  valve,  showing  outline  of  posterior  portion  of   visceral 
area  and  position  of  the  main  vascular  sinuses.     U.  S.  Nat.  Mus.  Cat.  No.  52529a. 
8a.  Partly  exfoliated  ventral  valve,  the  type  siiecimen.     U.  S.  Nat.  Mus.  Cat.  No.  52529b. 
8b.  Exterior  of  a  ventral  ?  valve.     U.  S.  Nat.  Mus.  Cat.  No.  52529c. 
8c.  Partly  exfoliated  dorsal  valve.     U.  S.  Nat.  Mus.  Cat.  No.  52529d. 

The  specimens  represented  are  all  from  Locality  CIO,  Middle  Cambrian  limestone  about  3  miles  southwest  of 
Yenchuang,  Sintai  district,  Shantung,  China. 

LiNGULELLA     (LiNGULEPIs)    EROS   (Walcott)    (p.  551). 

Figures  9  and  9a.  Ventral  and  dorsal  valves  restored  in  outline  from  other  specimens.  Locality  C7,  Middle  Cambrian 
limestone  2.2  miles  southwest  of  Yenchuang,  Sintai  district.  Shantung,  China.  U.  S.  Nat.  Mus. 
Cat.  Nos.  52527a  and  52527b,  respectively.     Figure  9  represents  the  type  specimen, 

Obolus  (Westonia)  blackwelderi  Walcott  (p.  453). 

Figure  10.  An  elongate  ventral  valve,  the  type  specimen,  with  posterior  portion  broken  away,  from  Locality  C6, 

Middle  Cambrian  shaly  limestone  2.5  miles  southwest  of  Yenchuang,  Sintai  district.  Shantung, 

China.     U.  S.  Nat.  Mus.  Cat.  No.  52540a. 
10a.  Short  form  of  ventral  valve  as.sociated  with  the  shell  represented  by  figure  10.     U.  S.  Nat.  Mus.  Cat.  No. 

52540b. 
10b.  Exterior  of  a  dorsal  valve  from  Locality  C2,  Middle  Cambrian  limestone  2  miles  south  of  Yenchuang, 

Sintai  district.  Shantung,  China.     IT.  S.  Nat.  Mus.  Cat.  No.  52541a. 
10c.  Enlargement  of  surface  of  a  shell  associated  with  the  ventral  valve  represented  by  figure  10.     L'.  S.  Nat. 

Mus.  Cat.  No.  52.540c. 

LiNGULELLA    HEBERTI  BaiTois   (p.  505). 

11.  Exterior  of  ventral  valve. 

11a.  Exterior  of  dorsal  valve. 

lib.  Cast  of  interior  of  ventral  valve,  the  type  specimen. 

lie.  Enlargement  of  the  outer  surface. 

Figures  11,  lla-c  are  copied  from  Barrois  [1882,  PI.  IV,  figs.  3a-d,  respectively].     The  specimens  represented 
are  all  from  Locality  350a,  Ordovician  sandstone  at  Cape  Vidio,  Province  of  Oviedo,  Spain. 

u  Now  referred  to  Obolus  ;  see  p.  489. 


PLATE    XL. 


135 


PLATE  XL. 

V.  Visceral  cavity. 

LiNGULELLA  (LiNGULEPIS)  ACUMINATA  (Conrad)  (p.  545). 

[PI.  XXXIV,  figs.  3,  3a-e;  Pi.  XLI,  figs.  1,  la-n;  and  PI.  XLII,  fljs.  1,  la  o.) 

Figure  1.  Ventral  valves,  the  type  specimens,  from  Locality  338s,  Upper  Cambrian  sandstone  at  High  Bridge  on 
Ausable  River,  Essex  County,  New  York.     Copied  from  Hall  [1847,  text  fig.,  p.  9],  who  states  that  the 
figure  is  copied  from  a  drawing  made  by  Conrad, 
la.  Ventral  valves  from  Locality  338s,  llpper  Cambrian  sandstone  at  High  IJridge  on  Ausable  River,  Essex 

County,  New  York.     Copied  from  Emmons's  figure  [1842,  text  fig.  68,  p.  2G8]  of  Lingula  anliqua. 
lb.  Partly  exfoliated  ventral  valve,  showing  the  visceral  cavity,  from  Locality  110,  Upper  Cambrian  sand- 
stone, east  side  of  the  town  of  Whitehall,  New  York.     U.  S.  Nat.  Mus.  Cat.  No.  51877a. 
Ic.  Narrow  ventral  valve  associated  on  the  same  slab  of  rock  with  figure  lb.     U.  S.  Nat.  Mus.  Cat.  No.  51877b. 
Id  and  le.  Dorsal  valves  associated  with  the  ventral  valves  represented  by  figures  lb  and  Ic.    U.  S.  Nat. 

Mus.  Cat.  Nos.  51877c  and  51877d,  respectively. 
If  and  Ig.  Small  ventral  and  dorsal  valves,  from  Locality  109,  Upper  Cambrian  sandstone  1.5  miles  south  of 

Deweys  Bridge  on  the  Champlain  Canal,  Washington  County,  New  York.     U.  S.  Nat.  Mus.  Cat. 

Nos.  51879a  and  51879b,  respectively. 
Ih.  Ventral  valve  from  Locality  76a,  Upper  Cambrian  arenaceous  limestone  1  mile  north  of  Saratoga  Springs, 

New  York.     U.  S.  Nat.  Mus.  Cat.  No.  52469a. 
li,  Ij,  and  Ik.  Ventral  valves,  from  Locality  76,  Upper  Cambrian  impure  limestones  4  miles  west  of  Saratoga 

Springs,  New  York.    U.  S.  Nat.  Mus.  Cat.  Nos.  51S78a,  51878b,  and  51878c,  respectively. 
1 1,  Im,  and  In.  Dorsal  valves  associated  with  the  specimens  represented  by  figures  li,  Ij,  and  Ik.     I'.  S. 

Nat.  Mus.  Cat.  Nos.  51878d,  51878e,  and  51878f,  respectively, 
lo.  A  broad  ventral  valve,  from  Locality  392,  Upper  Cambrian  Potsdam  sandstone.  Burgess,  Canada.     U.  S. 

Nat.  Mus.  Cat.  No.  17999a. 
Ip  and  Iq.  Narrow  and  broad  form  of  the  ventral  valve,  from  Locality  105,  Upper  Cambrian  limestone  at 

Bishops  Mill,    Hancock   County,    Tennessee.    U.    S.    Nat.    Mus.    Cat.    Nos.    51881a  and   51881b, 

respectively. 
Ir  and  Is.  Dorsal  valves  associated  with  the  ventral  valves  represented  by  figures  Ip  and  Iq.     U.  S.  Nat. 

Mus.  Cat.  Nos.  51881c  and  51881d,  respectively. 
136 


U.  S.   GEOLOGICAL  SURVEY 


MONOGRAPH  LI     PL.   XL 


FRANCES  WieSER  DEL. 


MCL10T*Pe     CO     I 


PLATE    XLI. 


137 


PLATE  XLI. 

k'.  Outer  lateral  space  of  area.  p.  Pedicle  groove, 

h.  Central  muscle  scar.  v.  \'i5ceral  cavity. 

J.  .\nterior  lateral  muscle  scar.  vs.  Main  vascular  si[iu5. 

LiNGULELLA   (LiNGULEPis)   ACUMINATA  (Conrad)    (p.  545). 

[PI.  XXXIV,  figs.  3,  3a-e;  PI.  XL,  figs.  1,  la-s;  and  I'l.  XLII,  figs.  1,  la-o.] 

Figure  1.  Slab  figured  by  Owon  [1852,  PI.  IB,  fig.  8]  as  Lingula  plnnaformis.     U.  S.  Nat.  Mus.  Cat.  No.  17860a. 

Locality  328h,  Upper  Cambrian  sandstone  at  the  falls  of  the  St.  Croix,  Polk  County,  Wisconsin, 
la,  lb,  and  Ic.  Partly  exfoliated  ventral  valves,  sho\ring  more  or  less  of  the  area  and  interior  vascular 

markings.     These  occur  in  Locality  82s,  Upper  Cambrian  sandstone  at  St.  Croix  Falls,  Wisconsin. 

U.  S.  Nat.  Mus.  Cat.  Nos.  51888a,  51888b,  and  51888c,  respectively. 
Id  and  le.  Ventral  valves  associated  ivith  the  shells  represented  by  figs.  la-c.     L'.  S.  Nat.  Mus.  Cat.  No3. 

51888d  and  51888e,  respectively. 
If.  Dorsal  valve  associated  with  specimen  represented  by  figure  la.     U.  S.  Nat.  Mus.  Cat.  No.  51888f. 
Ig.  Dorsal  valve  associated  with  the  specimen  represented  by  figure  la,  showing  the  area  and  the  central 

muscle  scars.     U.  S.  Nat.  Mus.  Cat.  No.  51888g. 
Ih.  Exfoliated  dorsal  valve  associated  with  specimen  represented  by  figure  la.     U.  S.  Nat.  Mus.  Cat.  No. 

51888h. 
li.  Ventral  valve,  from  Locality  79b,  Upper  Cambrian  sandstone  near  Hudson,  St.  Croix  County,  Wisconsin. 

U.  S.  Nat.  Mus.  Cat.  No.  51889a. 
Ij,  Ik,  and  1  1.     Exfoliated  dorsal  valves  associated  with  the  ventral  valve  reprgsented  by  figure  la.     U.  S. 

Nat.  Mus.  Cat.  Nos.  518881,  51888J,  and  51888k,  respectively. 
Im.  Dorsal  valve  associated  with  the  specimen  represented  by  figure  li.     U.  S.  Nat.  Mus.  Cat.  No.  51889b. 
In.  Small  exfoliated  ventral  valve,  from  Locality  84,  Middle  Cambrian  sandstone  at  Dresbach,  Winona  County, 

Minnesota.    U.  S.  Nat.  Mus.  Cat.  No.  51885a. 

LiNGULELLA    (LiNGULEPIs)    ACUMINATA    MEEKI    (Walcott)    (p.   550). 

Figures  2  and  2a.  Ventral  and  dorsal  valves  fnun  Locality  302b,  Middle  Cambrian  limstone  near  Crowfoot  Ridge 
Yellowstone  National  Park,  Wyoming.     U.  S.  Nat.  Mus.  Cat.  Nos.  35206a  and  35206b,  respectively. 
Figure  2  represents  the  type  specimen. 
138 


U.  S.  GEOLOGICAL  SURVEY 


MONOGRAPH   LI     PL.  XLI 


=;*ANCE8  WIESER  DEL. 


HEUOTVPE  CO..  BOSTON. 


PLATE   XLII. 


139 


PLATE  XLII. 


a.  Central  lateral  space  of  area, 
a'.  Outer  lateral  space  of  area. 
c.  Trapezoidal  area,  including  central,  middle 

lateral,  and  outside  lateral  muscle  scars, 
g.  ITmbonal  muscle  scar. 


h.  Central  mu.scle  scar. 
j.  Anterior  lateral  muscle  scar, 
p.  Pedicle  groove. 
V.  Visceral  cavity, 
vs.  Main  vascular  sinus. 


LiNGULELLA   (LiNGULEPIs)  ACUMINATA   (C'oniad)    (p.  545). 


|I1.  XXXIV,  figs.  3.  3a-e;  PI.  XI,.  figs.  1,  la-s:  and  IM.  XLI. 


.  1.  la-n.] 


FiGUBES  1  and  Id.  Narrow,  oxfciliated  ventral  valve  .showing  the  visceral  area.     The  .-^ide  view,  figure  Id,  shows  the 

outline  of  the  area  and  the  cast  of  the  pedicle  groove.     Locality  355,  Middle  Cambrian  sandstones  on 

Red  Canyon  Creek,  Black  Hills,  South  Dakota.     U.  S.  Nat.  Mus.  Cat.  No.  51894a. 
la  and  lb.  Broad  ventral  and  dorsal  valves,  identified  by  WTiitfield  as  LinguUpis  pinnaformis.     Locality  355, 

Middle  Cambrian  sandstones  on  Red  Canyon  Creek,  Black   Hills,  South  Dakota.    U.  S.  Nat.  Mus. 

Cat.  Nos.  24588a  and  2458Sb,  respectively. 
Ic.  Dorsal  valve  retaining  a  considerable  amount  of  ihe  laminated  portion  of  the  shell.     From  Locality  355d, 

Upper  Cambrian  friable  reddi.sh  sandstone.  Black  Hills,  South  Dakota.    U.  S.  Nat.  Mus.  Cat.  No.  51898a. 
le.  Cast  of  the  interior  of  a  ventral  valve  associated  with  the  shell  represented  by  fig.  Ic,  showing  area,  pedicle 

groove,  and   vascular  markings.     U.  S.  Nat.  Mus.  Cat.  No.  51S98b.     Another  specimen  (Cat.  No. 

51898c)  was  used  to  aid  in  restoring  this  figure. 
If.  Cast  of  the  interior  of  a  broad  dorsal  valve,  from  the  friable  purple  sandstones  of  Locality  355b,  Jliddle 

Cambrian,  on  Castle  Creek,  Black  Hills,  South  Dakota.     IT.  S.  Nat.  Mus.  Cat.  No.  1026b. 
Ig  and  Ih.  Casts  of  the  interior  of  broad  ventral  and  dorsal  valves.     From  Locality  355d,  Upper  Cambrian 

sandstone.  Black  Hills,  South  Dakota.     U.  S.  Nat.  Mus.  Cat.  Nos.  51898d  and  51S98e,  respectively. 
li  and  Ij.  Young  shells  that  occur  in  abundance  in  the  same  layers  with  the  specimens  represented  by  figures 

Ig  and  Ih.     L".  S.  Nat.  Mus.  Cat.  Nos.  51899a  and  51899b,  respectively. 
Ik,  11,  and  Im.  Ventral  valves  from  Locality  70,  Upper  Cambrian  limestones  on   Morgans  Creek,  Burnet 

County,  Texas.    U.  S.  Nat.  Mus.  Cat.  Nos.  51891a,  51891d,  and  51891b,  respectively. 
In.  Dorsal  valve  associated  with   the  ventral  valves  represented   by  figures  Ik,  11,  and  Im.     V .  S.  Nat. 

Mus.  Cat.  No.  51891c. 
lo.  Cast  of  interior  of  dorsal  valve,  showing  position  of  central  and  lateral  muscle  scars.     From  Locality  14b, 

Upper  Cambrian  limestone  on  Cold  Creek,  Llano  County,  Texas.     XJ.  S.  Nat.  Mus.  Cat.  No.  51892a. 

Obolus  (Westonia)  rogeksi  (Walcott)  (p.  463). 

Figure  2.  Partly  exfoliated  ventral  valve,  the  type  specimen,  illustrating  the  different  layers  forming  the  shell. 

U.  S.  Nat.  Mus.  Cat.  No.  27336a. 
2a.  Cast  of  the  interior  of  a  ventral  valve,  showing  the  area  and  vascular  markings.     U.  S.  Nat.  Mu.s.  Cat.  No. 

27336b. 
2b.  Cast  of  the  interior  of  a  ventral  valve  in  which  the  area  extends  far  down  the  cardinal  slopes.     L'.  S.  Nat. 

Mus.  Cat.  No.  27336c. 
2c.  Cast  of  the  interior  of  a  dorsal  valve,  showing  the  central  position  of  the  central  muscle  scars.     U.  S.  Nat. 

Mus.  Cat.  No.  27336d. 
2d.  Partly  exfoliated  dorsal  valve  on  which  a  i)or(ion  of  the  surface  of  the  outer  shell  is  preserved.     L^.  S. 

Nat.  Mus.  Cat.  No.  27336e. 

The  specimens  represented  are  all  from  Locality  343,  Lower  Ordovirian  limestone  pebbles  on  the  beach  near  New- 
port, Rhode  Island. 

Obolus  (Lingulobolus)  spissus  (Billings)  (p.  432). 

[II.  XVI,  figs.  2.  2a-k.] 

Figure  3.  Enlargement  of  the  surface  of  the  specimen  representcil  by  Plate  X\  I,  figure  2b,  of  this  monograph.     U.  S. 
Nat.  Mus.  Cat.  No.  51678b. 
3a.  Enlargement  of  the  outer  surface  of  the  inner  layer  in  front  of  iho  umbonal  muscle  scar,  of  the  dorsal  valve 
represented  by  Plate  XVI,  figure  2,  of  this  monograph.     U.  S.  Nat.  Mtis.  Cat.  No.  51678  1. 

The  specimens  represented  are  both  from  Locality  114b,  Upper  Cambrian  sandstone,  1  mile  north  of  Lance  Cove, 
Great  Belle  Island,  Conception  Bay,  Newfoundland. 
140 


U.  S.   GEOLOGICAL  SURVEY 


MONOGRAPH   LI     PL.XLII 


J_ 


A 


2" 


sg^^ps^ 


FRANCES  WIESEK  DEL 


HELIOTVPE  CO.,   BOSTON 


PLATE    XLIII. 


141 


PLATE  XLIII. 


a.  Central  lateral  space  of  area, 
a'.  Outer  lateral  space  of  area, 
c.  Trapezoidal  area,  iiHliidlng  central,  iiiWdle 

lateral,  and  outsiile  lateral  muscle  scars. 
f.  Flexure  line  of  area. 


h.  Central  muscle  scar, 
j.  -\nterior  lateral  muscle  scar, 
p.  Pedicrle  groove. 
vs.  Main  vascular  sinus. 
X.  Heart-shaped  cavity. 


If. 

Ig. 
Ih. 
li. 


LiNGULELLA    (LiNGULEPIs)    EXIGUA    (Matthcw)    (p.  551). 
[PI.  X.XXin.ligs.  4  and  4a.) 

FiGUR.  1.  Narrow  acuminata  ventral  valve  from  Locality  lot,  Middle  Cambrian  sandstone  on  McLean  Brook  near 
Marion  Bridge,  Cape  Breton,  Nova  Scotia.     U.  S.  Nat.  Mus.  Cat.  No.  347G6a  i^rook,  near 

'  S'm^^cS™ ;? S^: '-'-' ''- ''''  -'--'^-"  '^y  '"^^- ''  ^"' --'-^^  ^-^^  -  U.  S. 

lb.  Broader  form  of  ventral  valve  than  that  represented  by  figure  la,  but  a,ssociated  with  it      Specimens 
V  """.T-f^f        *'°"'  "^  ^"""  ^°'^^'^°  '^"""'^  1^  ^"^'  ^^  "'-'■"^  ^^  'he  collections.     U.  S.  Nat.  Mus.  Cat 

Ic.  still  broader  form  of  ventral  valve  intermediate  between  specimens  represented  by  figures  lb  and  If 
Associated  with  the  specimens  represented  by  figures  1,  la-b.     U.  S.  Nat.  Mus.  Cat   No  34766e 

Id.  S-al    V  ,     ,,th  slightly  roun.led  instead  of  straight  or  incurved  cardinal  slopes,  from  I  ocaHty 

3  ,  Mid<Ile  Cambrian  ^ndstone  on  McLean  Brook,  l.r,  miles  west  of  Marion  Bridge,  Cape  Breton 
Nova  Scotia.     U.  S.  Nat.  Mus.  Cat.  No.  34761a  g  .  "^"^pe  creion, 

^'''"  Na^'t^Mus^CaJ^No''  "'"'"''  ^'''"''  associated  with  the  specimen  represented  by  figure  Id.     U.  S. 
Elongate  and  attenuate  ventral  valve,  showing  cast  of  the  interior  surface,  also  a  portion  of  the  outer 
surface.     It  is  associated  with  the  shell  represented  in  figure  Id.     U.  S.  Nat.  Mus  Cat   No  34761d 

ngureld.     U.  S.  Nat.  Mus.  Cat.  No.  34761e. 

'^'"'''wftrtlf  "l^T""^  ventral  valve  compressed  and  flattened  in  the  arenaceous  shale.     It  is  associated 
with  the  shell  represented  in  figure  Id.     U.  S.  Nat.  Mus.  Cat  No  34761f 
Ij.  Cast  of  interior  of  a  broad  form  of  ventral  valve  somewhat  like  specimen  represented  by  figure  2c  in  outline 
1 1    Sn,  1      '  "T"'       "■'   u'^'  specimens  represented  by  figures  1,  la-c.     U.  S.  Nat.  Mus  Cat.  No  34766d' 

"'"'''^::Tti"^S^TZS;^'''-'-     — ^^-dwith.heshellrepresented 

m.  Fragment  of  arenaceous  shale  from  Locality  lOt  (see  fig.  1,  above),  with  a  group  of  small  shells  upon  it 

Natural  size.     U.  S.  Nat.  Mus.  Cat.  No.  34766f  ^ 

lo.  Cast  ;'f  the  interior  of  ventral  valve  showing  cast  of  pits  and  the  strong  ridges  of  the  main  vascular  canals, 

from  J-"caIity  31.  Middle  Cambrian  sandstone  on  McLean  Brook,  1..5  miles  west  of  Marion  Bridge 

tape  Breton,  Nova  Scotia.     V.  S.  Nat.  Mus.  Cat.  No.  34761  j 
Ip.  Part  of  the  interior  of  a  ventral  vah-e  associated  with  the  specimen  represented  by  figure  lo,  showin<.  the 

strong  ridges  beneath  the  main  va,srular  ..inusos.     U.  S.  Nat  Mus  Cat   No  .34761k 
Iq.  Cast  of  interior  of  a  ventral  valve,  showing  heart-shaped  area  (x),  trapezoidal  area  (c),  and  cast  of  vascular 

canal  ridges  (vs).     locality  10s,  Mid.lle  Cambrian  .xndstone  on  McLean  Brook,  near  Marion  BHd'e 

tape  Breton,  Nova  Scotia.     U.  S.  Nat.  Mus.  Cat.  No.  52468b 
Ir.  Cast  of  interior  of  a  <Iors;,l  valve  associated  «-ith  the  specimen  represented  bv  figure  Iq,  showing  area 

visceral  cavity,  and  portion  of  vascular  canal  ridges.     U.  S.  Nat.  Mus.  Cat.  No.  52468c      \notber 

1,    Cast  oTth  "'"T  ■      V    ^-  ''?"■;  ^'■"'"  ^°''^''y  ^'^  '"^^  "^^  *°  ^^'"'^  ^^^«*'"  P^^'i"'^^  "f  this  figure. 

of  the  interior  o  a  dors.il  va  ve  a.ssociated  ^Wth  the  specimen  represented  by  figure  lo,  showing  strongly 
marked  visceral  and  vascular  ridges.     U.  S.  Nat.  Mus.  Cat.  No  34761  1     "    "  '  ^         ^■ 

142 


U.  S.   GEOLOGICAL  SURVEY 


MONOGRAPH   LI     PL.  XLIII 


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Wm. 


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FRANCES  WIESER  DEL. 


LtOTVPE   CO    BCSTOM 


PLATE  XLIII.  143 

LiNGULELLA  (LiNGULEPis)  ExiGUA  (Matthcw) — Continued. 

Figure  It.  Large,  partly  exfoliated  dorsal  valve,  of  the  same  type  as  the  ventral  valve  represented  by  figure  1. 

Associated  with  the  specimen  represented  by  figure  Iq.     U.  S.  Nat.  Mus.  Cat.  No.  52468d. 
lu,  Iw,  and  Ix.  Casts  of  the  interior  of  dorsal  valves  showing  variation  in  outline,  form  of  visceral  cavity, 

pitting  of  inner  surface  of  valve,  etc.     Associated  with  the  specimen  represented  by  figure  Iq.     U.  S. 

Nat.  Mus.  Cat.  Nos.  34761m,  34761o,  and  34761p,  respectively. 
Iv.  Interior  of  a  dorsal  valve  associated  with  the  specimen  represented  by  figure  Iq,  in  which  the  pits  are 

arranged  like  beads  along  the  lines  of  growth.     U.  S.  Nat.  Mus.  Cat.  No.  347f)ln. 
ly.  Part  of  interior  of  dorsal  valve  associated  with  the  specimen  represented  by  figure  Iq,  showing  ridges 

on  which  the  central  muscle  scars  occur,  main  vascular  canal  ridges,  and  fine  pitting  of  surface.     U.  S. 

Nat.  Mus.  Cat.  No.  34761q. 
Iz.  Cast  of  interior  of  dorsal  valve  in  which  the  visceral  area  extends  well  toward  the  front.     Locality  llz, 

Middle  Cambrian  sandstone  on  Big  Ridge,  2  miles  south  of  Marion  Bridge,  Cape  Breton,  Nova  Scotia. 

U.  S.  Nat.  Mus.  Cat.  No.  51870a. 


PLATE   XLIT 


62667°— VOL  51,  pt  2—12 10  145 


PLATE  XLIV. 

a.  Central  lateral  space  of  area.  p.  Pedicle  groove. 

h.  Central  muscle  scar.  v.  Visceral  cavity. 

LiNGULELLA   (LiNGULEPis)  GREGWA   (Matthew)  (p.  5.54). 

Figure  1.  Very  perfect  ventral  valve  preserving  the  entire  exterior  .«urfare,  from  Loealily  lOp",  Middle  Cambrian 

sandstones  between  Indian  River  and  McPhees  Brook,  Cape  Breton,  Nova  Scotia.     U.  S.  Nat.  Mus. 

Cat.  No.  51875a. 
la.  Cast  of  the  interior  of  a  ventral  valve  from  Locality  lOp,  Middle  Cambrian  sandstones  of  Division  E2b, 

Dugald  Brook,  Cape  Breton,  Nova  Scotia,  showing  the  vascular  sinuses.     U.  S.  Nat.  Mus.  Cat.  No. 

51873a. 
lb.  Enlargement  of  a  small  ventral  valve  associated  with  the  shell  represented  by  figure  la.     U.  S.  Nat.  Mus. 

Cat.  No.  51873b. 
Ic.  Elongate  ventral  valve  from  Locality  lOp',  Middle  Cambrian  sandstones  on  Gregwa  Brook,  Cape  Breton, 

Nova  Scotia.     U.  S.  Nat.  Mus.  Cat.  No.  51874a. 
Id.  Partly  exfoliated  ventral  valve  a-ssociated  with  the  shell  represented  by  figure  la.     U.  S.  Nat.  Mus. 

Cat.  No.  51873c. 
le.  Small  ventral  valve  associated  with  the  shell  represented  by  figure  Ic,  showing  the  cast  of  a  long  pedicle 

furrow  and  a  portion  of  the  area.     U.  S.  Nat.  Mus.  Cat.  No.  51874b. 
If.  Cast  of  the  interior  of  a  very  broad  ventral  valve  associated  with  the  shell  represented  by  figure  1,  on  which 

a  portion  of  the  outer  shell  is  preserved.     U.  S.  Nat.  Mus.  Cat.  No.  51875b. 
Ig.  Fragment  of  small  ventral  valve  associated  with  the  shell  represelited  by  figure  1,  showing  the  area  and 

the  character  of  the  outer  surface  of  the  shell.     U.  S.  Nat.  Mus.  Cat.  No.  51875c. 
Ih.  Cast  of  part  of  the  interior  of  a  small  dorsal  valve  associated  with  the  specimen  represented  by  figure  la. 

U.  S.  Nat.  Mus.  Cat.  No.  51873e. 
•        li.  Small  o\al  dorsal  valve  associated  with  the  specimen  represented  by  figiu-e  la.     U.  S.  Nat.  Mus.  Cat. 

No.  51873f. 
Ij.  Transversely  oval  dorsal  valve,  preserving  the  outer  surface,  associated  with  the  specimen  represented 

by  figure  la.     U.S.Nat.Mus.  Cat.  No.  51873g.    The  outer  surface  of  this  shell  is  enlarged  in  figure  Ip. 
Ik.  Cast  of  the  interior  of  a  subtriangular  dorsal  valve,  showing  the  -s-isceral  area,  associated  with  the  shell 

represented  by  figure  la.     U.  S.  Nat.  Mus.  Cat.  No.  51873h. 
11.  Cast  of  the  interi<ir  of  an  elongate  dorsal  valve  associated  with  the  shell  represented  by  figxire  la.     U.  S. 

Nat.  Mus.  Cat.  No.  51873d. 
Im.  Cast  of  the  interior  of  an  elongate  dorsal  valve  associated  with  the  shell  represented  by  figure  Ic.     U.  S. 

Nat.  Mus.  Cat.  No.  51874c. 
In.  Cast  of  the  interior  of  a  dorsal  valve  associated  with  the  shell  represented  by  figure  Ic.     V.  S.  Nat.  Mus. 

Cat.  No.  51874d.     The  concentric  lines  of  tubercles  have  been  drawn  in  from  other  specimens  (Cat. 

Nos.  518731  and  51873J  from  Locality  lOp). 
lo.  Enlargement  of  a  portion  of  surface  of  a  very  perfectly  preserved  dorsal  valve  12  mm.  in  length  from 

Locality  13t",  Middle  Cambrian  sandstones  of  Divisions  Elc  and  Eld  on  Dugald  Brook,  Cape  Breton, 

Nova  Scotia.     V.  S.  Nat.  Mus.  Cat.  No.  56792a. 
Ip.  Enlargement  of  the  surface  of  the  dorsal  valve  represented  in  figure  Ij  to  t^how  the  irregular,  concentric, 

undulating  ridges.     V.  S.  Nat.  Mus.  Cat.  No.  51873g. 

LiNGULELLA  (LiNGTJLEPis)  LONGiNERVis   (Matthew)  (p.  555). 

Figures  2  and  2a.  Exteriors  of  two  small  ventral  valves,  with  nearly  straight  cardinal  margins.     Locality  13p,  Middle 

Cambrian  sandstones  40  feet  above  Di^•ision  E2a  on  Dugald  Brook,  Cape  Breton,  Nova  Scotia.     U.  S. 

Nat.  Mus.  Cat.  Nos.  51872a  and  51872b,  respectively. 
2b.  Partly   exfoliated   ventral   valve,  with  incurved   cardinal   margins.     Locality   13g,  Middle   Cambrian 

sandstones  10  feet  above  Division  E2a,  Dugald  Brook,  Cape  Breton,  Nova  Scotia.     U.  S.  Nat.  Mus. 

Cat.  No.  56977a. 
2c.  Interior  of  a  broken  ventral  valve,  showing  visceral  cavity,  area  of  central  muscle  scars,  etc.     Locality 

13f,  Middle  Cambrian  sandstones  20  feet  above  Division  E2a,  Dugald  Brook,  Cape  Breton,  Nova 

Scotia.     U.  S.  Nat.  Mus.  Cat.  No.  56974a. 
2d.  Exterior  of  a  dorsal  valve  from  Locality  lOp,  Middle  Cambrian  sandstones  of  Di\'ision  E2b,  on  Dugald 

Brook,  Cape  Breton,  Nova  Scotia.     U.  S.  Nat.  Mus.  Cat.  No.  34764a. 
2e.  Interior  of  a  dorsal  valve  from  Locality  344o,  Middle  Cambrian  sandstones  of  Division  E2b,  on  Dugald 

Brook,  Cape  Breton,  Nova  Scotia.     Univer.'^ily  of  Toronto,  <  inada.     Specimen  figured  by  Matthew 

[1903,  PI.  VII,  fig.  6f].     The  two  figures  should  be  compared. 
2f  and  2g.  Casts  of  j>arts  of  interiors  of  dorsal  valves,  .showing  position  of  central  scars.     Locality  13d,  Middle 

Cambrian  sandstones  between  Divisions  E2a  and  E2b,  Dugald  Brook,  Cape  Breton,  Nova  Scotia. 

r.  S.  Nat.  Mus.  Cat.  Nos.  56976a  and  56976b,  respectively. 
146 


U.  S.   GEOLOGICAL  SURVEY 


MONOGRAPH   LI     PL.  XLIV 


FRANCES  WIE8ER  DEL 


'OE    CO   90ST-OV 


PLATE   XLV. 


147 


PLATE  XLV. 

c.  Trapezoidal  area,  including  central,  middle  s.  Median  septum, 

lateral,  and  outside  lateral  muscle  scars.  v.  Visceral  cavity, 

h.  Central  muscle  scars.  vs.  Main  vascular  sinus, 

j.  Anterior  lateral  muscle  scars.  x.  Heart-shaped  cavity 
ps.  I'arietal  band. 

LlNGULELLA    RADULA    MattlieW    (p.  529).  . 

Figure  1.  Imperfect  ca.st  of  the  interior  of  a  ventral  valve  from  Locality  301x,  Upper  Cambrian  sandstones  of  Divi- 
sion 2c  of  Matthew's  section,  Dunns  Shore,  Simonds,  near  St.  John,  New  Brunswick.  University 
of  Toronto,  Canada. 

la.  Cast  of  an  interior  of  a  ventral  valve  from  Locality  301y,  L'pper  Cambrian  sandstones  of  Division  2c, 
east  side  of  Courtney  Bay,  St.  John,  New  Brunswick.     University  of  Toronto,  Canada. 

lb.  Slightly  distorted  ventral  valve  from  the  same  locality  as  specimen  represented  by  figure  la.  University 
of  Toronto,  Canada. 

Ic.  Cast  of  the  interior  of  a  distorted  ventral  valve,  associated  with  specimen  represented  by  figure  la.  Uni- 
versity of  Toronto,  Canada. 

Id.  Cast  of  the  interior  of  a  dorsal  valve,  the  type  specimen,  showing  central  scars,  etc.,  a.ssociated  with  the 
specimen  represented  by  figiu'e  1.     University  of  Toronto,  Canada. 

Figures  1,  la-d,  and  If  are  drawn  from  the  specimens  upon  which  Matthew  based  his  figures  [1891,  PI.  XV,  figs. 
7a-b  and  8a-e],  but  closer  identification  is  impossible. 

le.  Cast  of  the  interior  of  a  distorted  ventral  valve  from  the  locality  represented  l)y  figure  la.  Museum  of 
Comparative  Zoology,  Cambridge,  Massachusetts. 

If.  Cast  showing  part  of  the  interior  of  a  dorsal  valve,  associated  with  the  specimens  represented  by  figures 
la-c.     University  of  Toronto,  Canada.     (See  note  following  the  description  of  figure  Id.) 

Ig.  Small  ventral  valve,  preser\-ing  the  exterior  surface  and  convexity  of  outline  in  an  unusually  perfect 
manner.  Locality  same  as  specimen  represented  by  figure  la.  Museum  of  Comparative  Zoology, 
Cambridge,  Massachusetts.     (See  note  in  description  of  figures  Ik  and  11.) 

Ih.  Interior  of  a  ventral  valve,  preserving  the  form  of  the  heart-shaped  cavity  as  in  Obolus,  Locality  same 
as  specimen  represented  by  figure  la.     Museum  of  Comparative  Zoology,  Cambridge,  ilassachusetts. 

li.  Cast  of  the  interior  of  a  ventral  valve,  sho\ving  the  \-isceral  cavity  and  main  vascular  sinuses  with  unusual 
clearness.  Locality  same  as  specimen  represented  by  figure  la.  Museum  of  Comparative  Zoology, 
Cambridge,  Massachusetts. 

Ij.  Cast  of  the  interior  of  a  dorsal  valve,  showing  muscle  scars,  etc.,  beautifully  preserved.  Locality  same  as 
specimen  represented  by  figiu-e  la.     Museum  of  Comparative  Zoology,  Cambridge,  Massachusetts. 

Ik  and  1 1.  Interior  of  dorsal  valve  and  cast  of  same.  Locality  same  as  specimen  represented  by  figure  la. 
Museum  of  Comparative  Zoology,  Cambridge,  Mas.sachusetts.  It  may  be  that  the  specimens  repre- 
sented by  figures  Ig,  Ik,  and  1 1  represent  a  small  species  distinct  from  Lingiilella  raditla.  All  of  the 
specimens  are  more  or  less  distorted  in  the  arenaceous  shales  in  which  (hey  are  embedded. 

LlNGULELLA    TRIPARILIS    (MattllCW)     (p.  536). 

[Text  figs.  44a-;,  p.  537.] 

Figure  2.  Broad  form  of  ventral  valve  from  Locality  13t',  Middle  Cambrian  sandstones  of  Division  Elb  on  Dugald 

Brook,  Cape  Breton,  Nova  Scotia.     U.  S.  Nat.  Mus.  Cat.  No.  57013a. 
2a  and  2a'.  Narrow  form  of  ventral  valve  associated  with  the  specimen  represented  by  figure  2.     U.  S.  Nat. 

Mus.  Cat.  No.  57013b. 
2b.  Ventral  valve  on  which  a  portion  of  the  exterior  surface  of  the  shell  is  preserved.     Associated  with  the 

specimen  represented  by  figure  2.     U.  S.  Nat.  Mus.  Cat.  No.  57013c. 
2c.  Cast  of  interior  of  a  dorsal  valve  associated  with  the  specimen  represented  by  figure  2.     I'.  S.  Xat.  Mus. 

Cat.  No.  57013d. 
2d.  Cast  of  interior  of  a  dorsal  valve  from  Locality  13t",  Middle  Cambrian  sandstones  of  DiWsions  Elc  and  Eld, 

on  Dugald  Brook,  Cape  Breton,  Nova  Scotia.     V.  S.  Nat.  Mus.  Cat.  No.  57012a. 
2e.  Narrow  form  of  dorsal  valve  associated  with  the  specimen  represented  by  figure  2,  preser\-ing  a  portion 

of  the  outer  shell,  with  side  outline.     U.  S.  Nat.  Mus.  Cat.  No.  57013e.     Another  specimen  (Cat. 

No.  51855a,  from  Locality  13t)  was  used  in  restoring  certain  portions  of  this  figure. 
2f.  Broad  form  of  dorsal  valve,  associated  with  the  specimen  represented  by  figure  2.     U.  S.  Nat.  Mus.  Cat- 
No.  57013f. 
148 


U.  S.   GEOLOGICAL  SURVEY 


MONOGRAPH   LI     PL.  XLV 


PS  y.i. 


2"' 


i 


PRANCES  WIESER  DEL. 


HELioTYPE  CO  eosi 


PLATE  XLV.  149 

LiNGULELLA   (LiNGTJLEPis)  PUMiLA   (Matthew)  (p.  556). 

Figure  3.  Exterior  of  ventral  valve,  the  type  specimen.     University  of  Toronto,  Canada. 
3a.  Exfoliated  dorsal  valve,  showing  muscle  scars.     University  of  Toronto,  Canada. 

Figures  3  and  3a  are  drawn  from  the  specimens  illustrated  by  Matthew  [1903,  PI.  VII,  figs.  5a  and  5b,  respectively]. 
The  specimens  represented  are  both  from  Locality  344f,  Middle  Cambrian,  shalesof  the  Coldbrook  of  Matthew,  on  Dugald 
Brook,  Cape  Breton,  Nova  Scotia. 


PLATE    XL VI. 


151 


PLATE  XLVI. 

a.  Central  lateral  space  of  area.  f.  Flexure  line  of  area, 

a'.  Outer  lateral  space  of  area.  p.  Tedicle  groove. 

c.  Trapezoidal  area,  including  central,  middle  v.  Visceral  cavity, 
lateral,  and  outside  lateral  muscle  scars. 

Obolus  (Westo?:ia)  aurora  (Hall)  (p.  451). 

Figure  1.  Compressed  ventral  valve,  from  which  the  outer  shell  has  been  exfoliated.     Locality  S85x,  Upper  Cambrian 

sandstone  near  Mazomanie,  Dane  County,  Wisconsin.     U.  S.  Nat.  Mus.  Cat.  No.  51681a.     The  area 

is  enlarged  in  figure  Ic. 
la.  Cast  of  the  interior  of  a  compressed  ventral  xalve  associated  with  the  specimen  represented  by  figure  1. 

The  visceral  area  (v)  recalls  the  heart-shaped  pit  of  Lingulella  anitangida  (PI.  XVII,  fig.  If).    The 

central  muscle  scars  were  located  in  the  area  (c),  but  are  not  clearly  defined.     IJ.  S.  Nat.  Mus.  Cat. 

No.  51681b. 
lb.  Compressed  ventral  valve  associated  with  the  specimen  represented  by  figure  1,  showing  concentric  and 

radiating  lines  and  strise  as  preserved  on  the  cast  of  the  interior  of  the  shell.     U.  S.  Nat.  Mus.  Cat. 

No.  51681c.     The  area  is  enlarged  in  figure  Id. 
Ic.  Enlargement  of  the  area  of  figure  1.     U.  S.  Nat.  Mus.  Cat.  No.  51681a. 
Id.  Enlargement  of  the  area  of  figure  lb,  to  show  the  apron-like  area  mentioned  in  the  text  (p.  452).     U.  S. 

Nat.  Mus.  Cat.  No.  51681c. 
le.  Cast  of  the  exterior  of  a  dorsal  valve  associated  with  the  specimen  represented  by  figure  1.     U.  S.  Nat. 

Mus.  Cat.  No.  51681d. 
If.  Cast  of  the  interior  of  a  dorsal  vahe  associated  with  the  specimen  represented  by  figure  1.     The  shell  is 

compressed  and  the  area  broken  at  x'.     U.  S.  Nat.  Mus.  Cat.  No.  516Sle. 
Ig.  Enlargement  of  a  portion  of  the  central  part  of  the  surface  of  the  shell  figured  in  ]h,  to  show  the  irregular 

lamellose  character  of  the  striae.     Locality  85s,  Upper  Cambrian  sandstone  at  Prairie  du  Sac,  Sauk 

County,  Wisconsin.     U.  S.  Nat.  Mus.  Cat.  No.  51G80a. 
Ih.  Part  of  the  shell  represented  in  figure  Ig,  greatly  enlarged  by  photography  to  illustrate  the  character  of 

the  outer  surface.     U.  S.  Nat.  Mus.  Cat.  No.  61680a. 
1.52 


U.  S.   GEOLOGICAL  SURVEY 


MONOGRAPH    LI      PL.  XLVI 


FRANCES  W'ESER  DEL. 


MELlOTypE   CO    BCSl 


PLATE   XLVII. 


153 


PLATE  XL VII. 

a.  Central  lateral  space  of  area.  p.  Pedicle  groove, 

a'.  OutfT  lat^?ral  space  of  area.  ps.  Parietal  band, 

f.  Fle-Kure  line  of  area.  s.  Median  septum, 

h.  Central  muscle  scar.  v.  Vi.sceral  cavity. 

i.  Transmedian  muscle  scar.  vs.  Main  vascular  sinus, 

j.  Anterior  lateral  muscle  scar. 

Obolus  (Westonia)  ell.\  (Hall  and  Whitfield)  (p.  455). 

|PI.  XXXIII.  figs.  3,  3a-c.] 

Figure  1.  Ventral  valve  laterally  compressed  and  flattened,  from  Locality  30a,  Middle  Cambrian  siliceous  shale  in 

Big  Cottonwood  Canyon,  southeast  of  Salt  Lake  City,  Utah.     V .  S.  Nat.  Mus.  Cat.  No.  51691a. 
la.  Dorsal  valve  associated  in  the  same  bed  of  shale  vrith  specimen  represented  by  figure  1,  but  it  is  not  com- 
pressed laterally.     Neither  specimen  preserves  any  of  the  shell  substance.     V.  S.  Nat.  Mus.  Cat.  No. 

51691b. 
lb.  Enlarged  figure  of  the  type  specimen,  a  dorsal  valve,  from  Locality  329,  Middle  Cambrian  shales  near 

Calls  Fort,  Boxelder  County,  Utah.    U.  S.  Nat.  Mus.  Cat.  No.  15321a.     Specimen  figured  by  Hall 

and  \\Tiitfield  [1877,  PI.  I,  fig.  8]  as  Lingidepis  ella;  and  by  Walcott  [1886b,  PI.  VIII,  fig.  4;  and  1891a, 

PI.  LXVII,  fig.  2b]  as  Lingulella  ella. 
Ic.  Cast  of  the  interior  of  a  slightly  distorted  ventral  valve  from  Locality  329e,  Middle  Cambrian  siliceous 

shales  of  East  Canyon,  above  Ophir,  Oquirrh  Range,  Tooele  County,  L'tah.     U.  S.  Nat.  Mus.  Cat. 

No.  1.5320a. 
Id.  Another  cast  of  the  interior  of  a  ventral  valve  that  is  associated  with  the  specimen  represented  by  figure 

Ic,  but  which  has  suffered  less  from  distortion.     U.  S.  Nat.  Mus.  Cat.  No.  1.5320b.     Specimen  figured 

by  Walcott  [lS98b,  PI.  XXVIII,  fig.  7]  as  Oholus  {Lingulella)  ella. 
le  and  If.  Ventral  and  dorsal  valves  of  young  shells  associated  with  the  shells  represented  by  figures  1  and 

la.     U.  S.  Nat.  Mus.  Cat.  Nos.  51691c  and  51691d,  respectively. 
Ig.  Impression  of  the  interior  of  a  ventral  valve  from  Locality  302s,  Middle  Cambrian  shale  in  Last  Chance 

Gulch,  south  of  Helena,  Montana.     U.  S.  Nat.  Mus.  Cat.  No.  516S6a.     Specimen  figured  by  Walcott 

[1898b,  PI.  XXVIII,  fig.  5]  as  Obolus  (Lingulella)  ella. 
Ih  and  li.  Interior  casts  of  ventral  and  dorsal  valves  flattened  in  argillaceous  shales  of  Locality  31,  Middle 

Cambrian,  at  the  Chisholm  mine,  near  Pioche,  Nevada.     LT.  S.  Nat.  Mus.  Cat.  Nos.  15319a  and  1.5319b, 

respectively.     The  specimen  represented  by  figure  li  was  figured  by  Walcott  [1898b,  PL  XXVIII, 

fig.  8]  as  Obolus  {Lingulella)  ella. 
Ij.  Cast  of  the  interior  of  a  small  ventral  valve  with  a  very  high  area,  from  Locality  4g,  Middle  Cambrian  shale 

1  mile  north  of  the  forks  of  East  and  West  Gallatin  rivers,  Montana.     L'.  S.  Nat.  Mus.  Cat.  No.  51GS5a. 
Ik.  Impression  of  the  interior  of  a  slightly  distorted  dorsal  valve  from  the  same  locality  as  specimen  repre- 
sented by  figure  Ig,  showing  the  characteristic  muscular  impressions.     U.  S.  Nat.  Mus.  Cat.  No. 

51686b.     Specimen  figured  by  Walcott  [1898b,  PI.  XXVIII,  fig.  6]  as  Obolus  (Lingulella)  ella. 
1 1.  Interior  of  finely  preserved  dorsal  valve  from  Locality  5h,  Middle  Cambrian  shales  2  miles  southeast  of 

Malade,  Idaho.     U.  S.  Nat.  Mus.  Cat.  No.  51689a. 
Im.  Enlargement  of  a  small  individual  associated  with  the  shells  repre.sented  by  figures  Ih  and  li,  showing 

characteristic  surface  markings.     V .  S.  Nat.  Mus.  Cat.  No.  15319c.     The  counteq^art  of  this  specimen 

(Cat.  No.  15319d)  was  used  to  aid  in  restoring  certain  portions  of  figure  Im. 
In.  Cast  of  an  interior  of  a  ventral  valve  associated  with  the  ventral  valve  represented  by  figure  Ij.     L^  S. 

Nat.  Mus.  Cat.  No.  5168.5b. 
lo.  Enlargement  by  photography  of  the  surface  of  a  specimen  associated  with  the  shell  represented  by  figure 

Ij.     U.  S.  Nat.  Mus.  Cat.  No.  51685c. 
Ip.  Distorted  ventral  valve  from  Locality  90,  Middle  Cambrian  shales  near  Craigs  Mountain,  Cherokee  County, 

Alabama.     U.  S.  Nat.  Mus.  Cat.  No.  51634a. 
154 


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MONOGRAPH    LI     PL.  XLVII 


PRANCES  WIESER  DEL. 


:  CO  BOSTON 


PLATE    XL VIII. 


155 


PLATE  XLVIII. 

h.  Central  muscle  scar.  vs.  Main  vascular  sinus. 

1.  Outside  lateral  muscle  scar.  x.  Heart-shaped  cavity. 

V.  Visceral  cavity. 

Obolus  (Westonia)  euglyphus  (Walcott)  (p.  461). 

Figures  1  and  la.  Two  aasiociatod,  partly  exfoliated  ventral  valves  that  illustrate  variation  in  form,  and  the  strong 
lamellje  of  the  anterior  portion  of  the  shell.  Locality  74,  Middle  Cambrian  sandstone  at  the  head  of 
Nunkoweap  Valley,  Grand  Canyon  of  the  Colorado,  Arizona.  U.  S.  Nat.  Mus.  Cat.  No.  2731Ca  and 
27316b,  respectively. 

lb.  Exfoliated  ventral  valve  associated  with  the  specimens  represented  by  figures  1  and  la,  showing  the  fine 
radiating  strise  on  the  inner  layer  of  the  shell.    U.  S.  Nat.  Mus.  Cat.  No.  27316c. 

Ic.  Cast  of  the  interior  of  a  ventral  valve,  the  type  specimen,  associated  with  the  Bpecimens  represented  by 
figures  1  and  la,  showing  the  character  of  the  area,  visceral  cavity,  and  main  vascular  sinuses.  U.  S. 
Nat.  Mus.  Cat.  No.  273l6d. 

Id.  Cast  of  the  interior  of  a  ventral  valve  from  Locality  74c,  Middle  Cambrian  sandstone  at  the  head  of  Lava 
Canyon,  Grand  Canyon  of  the  Colorado,  Arizona.     U.  S.  Nat.  Mus.  Cat.  No.  57023a. 

le.  Cast  of  the  interior  of  a  dorsal  valve,  associated  with  the  specimen  represented  by  figure  Id.  L^.  S.  Nat. 
Mus.  Cat.  No.  57023b.  Another  specimen  (Cat.  No.  27316e  from  Locality  74)  was  used  to  aid  in  restor- 
ing certain  portions  of  this  figure. 

If.  Enlargement  of  a  portion  of  the  surface  near  the  umbo,  to  illustrate  the  irregular  inosculating  strise. 
Associated  with  the  shells  represented  by  figures  1  and  la.    U.  S.  Nat.  Mus.  Cat.  No.  27316f. 

LiNGtILELLA    LIXEOLATA    (Walcott)     (p.  515). 

FiGUBE  2.  Small,  obtuse  ventral  valve  from  which  the  shell  has  been  largely  exfoliated.  Locality  73a,  Middle  Cam- 
brian sandstone  in  Chuar  Valley,  CJrand  Canyon  of  the  Colorado,  Arizona.  U.  S.  Nat.  Mus.  Cat.  No. 
27324a. 

2a.  Acuminate  ventral  valve  associated  with  the  shell  represented  by  figure  2,  showing  a  portion  of  the  inner 
layers,  marked  by  fine  radiating  stri.f.     U.  S.  Nat.  Mu.-!.  Cat.  No.  27324b. 

2b.  Very  perfect  dorsal  valve,  the  type  specimen,  from  Locality  73,  Middle  Cambrian  sandstones  in  Kwagunt 
Valley,  Grand  Canyon  of  the  Colorado,  Arizona.     V.  S.  Nat.  Mus.  Cat.  No.  27325a. 

2c  and  2d.  Partly  exfoliated  dorsal  valves  associated  with  the  shell  represented  by  figure  2.  U.  S.  Nat. 
Mus.  Cat.  Nos.  27324c  and  27324d,  respectively. 

2e  and  2f .  Associated  ventral  and  dorsal  valves  from  Locality  74,  Middle  Cambrian  sandstones  at  the  head  of 
Nunkoweap  Valley,  Grand  Canyon  of  the  Colorado,  Arizona.  U.  S.  Nat.  Mus.  Cat.  Nos.  27326a  and 
27326b,  respectively. 

2g.  Partly  exfoliated  dorsal  valve,  more  broadly  oval  than  usual,  associated  with  the  shell  represented  by 
figure  2b.     U.  S.  Nat.  Mus.  Cat.  NcJ.  27325b. 

2h.  A  very  fine  illustration  of  a  rather  large  dorsal  valve,  associated  with  the  shell  represented  by  figure  2b. 
U.  S.  Nat.  Mus.  Cat.  No.  27325c. 

2i  and  2j.  United  ventral  and  dorsal  valves  with  side  view,  from  Locality  74d,  Middle  Cambrian  sandstone  in 
Bass  Canyon,  Grand  Canyon  of  the  Colorado,  Arizona.     U.  S.  Nat.  Mus.  Cat.  No.  51820a. 

2k  and  21.  Casts  of  rather  large  ventral  and  dorsal  valves  that  are  referred  to  this  species.  They  are  associ- 
ated with  the  shell  represented  by  figure  2.    U.  S.  Nat.  Mus.  Cat.  Nos.  27324e  and  27324f,  respectively. 

Obolus  (Westonia)  finlandensis  Walcott  (p.  462). 

Figure  3.  Exterior  of  ventral  valve,  the  type  specimen,  illustrating  form  and  surface  characters.     IT.  S.  Nat.  Mus. 
Cat.  No.  35296a. 
3a.  Partly  exfoliated  dorsal  valve.     U.  S.  Nat.  Mus.  Cat.  No.  35296b. 
3b.  Cast  of  part  of  interior  of  dorsal  valve.     U.  S.  Nat.  Mus.  Cat.  No.  3529r)C. 

The  specimens  represented  are  all  from  Locality  311x,  Middle  Cambrian  limestone  at  Saltvik,  Aland  Island, 
Finland. 

156 


U.  S.   GEOLOGICAL  SURVEY 


MONOGRAPH    LI     PL.  XLVIIl 


FRANCES  WIE8ER  DEL. 


HCLIOTVPE   CC   BOSTON 


PLATE  XLVIII.  157 

Obolus  (Westonia)  bottnicus  (Wiman)   (p.  454). 

Figures  4  and  4'.  Top  and  side  viewM  of  an  almoat  perfectly  preserved  ventral  valve,  the  type  specimen.     Specimen  in 

the  collection  of  the  University  of  Upsala,  Sweden;  cast  in  the  United  States   National   Musenm 

(Cat.  No.  57089a). 
4a.  Exterior  of  a  partly  exfoliated  dorsal  valve.     Specimen  in  the  collection  of   the  University  of  Upsala, 

Sweden;  cast  in  the  United  States  National  Museum  (Cat.  No.  57089b.) 
4b.  Imperfect  cast  of  the  interior  of  a  dorsal  valve.     Specimen  in  the  collection  of  the  University  of  Upsala, 

Sweden;  cast  in  the  United  States  National  Museum  (Cat.  No.  57089c). 
4c.  Interior  of  a  dorsal  valve.     Specimen  in  the  collection  of  the  University  of  Upsala,  Sweden;  ca.st  in  the 

United  States  National  Museum  (Cat.  No.  o7089d). 

Figures  4,  4a-c  are  drawn  from  the  specimens  illustrated  by  Wiman  [1902,  PI.  II,  figs.  41^4,  respectively]  as 
Lingula  hottnica.  The  specimens  represented  are  all  from  Locality  311,  Middle?  Cambrian  drift  bowlder  of  sandstone 
on  Eggegrund  Island,  Gefle  Bay,  Sweden. 

Obolus  (Westonia)  wimani  Walcott  (p.  467). 

Figure  5.  Exterior  of  ventral  valve  from  Locality  311c,  Middle?  Cambrian  drift  bowlder  No.  7  on  Biludden, 
Gefle  Bay,  Sweden.  Specimen  in  the  collection  of  the  L^niversity  of  Up.sala,  Sweden;  cast  in  the 
United  States  National  Museum  (Cat.  No.  57090a).  Type  specimen,  figured  by  Wiman  [1902,  PI.  II, 
fig.  30]  as  Lingalella  sp.  No.  1. 

5a.  Exterior  of  ventral  valve  from  Locality  311g,  Middle?  Cambrian  drift  bowlder  No.  16  on  Biludden, 
Gefle  Bay,  Sweden.  Specimen  in  the  collection  of  the  University  of  Upsala,  Sweden;  cast  in  the 
United  States  National  Museum  (Cat.  No.  57091a).  Specimen  figured  by  Wiman  [1902,  PI.  II,  fig. 
31]  as  LinguleUa  sp.  No.  2. 

5b.  Partly  exfoliated  dorsal  valve  from  Locality  3Ht,  Middle  ?  Cambrian  drift  bowlder  at  Ofverby,  Aland 
Island,  Finland.  Specimen  in  the  collection  of  the  ITniversity  of  L'psala,  Sweden;  cast  in  the  United 
States  National  Museum  (Cat.  No.  57092a).  Specimen  figured  by  ^\■iman  [1902,  PI.  II,  fig.  32]  as 
LinguleUa  sp.  No.  7. 

Obolus  (Westonia)  alandensis  Walcott  (p.  4,51). 

Figure  6.  Exterior  of  ventral  valve  from  Locality  311j,  Middle?  Cambrian  drift  bowlder  No.  28  on  Biludden, 
Gefle  Bay,  Sweden.  Specimen  in  the  collection  of  the  University  of  Upsala,  Sweden;  cast  in  the 
United  States  National  Museum  (Cat.  No.  57093a).  Specimen  figured  by  Wiman  [1902,  PI.  II,  fig. 
33]  as  LinguleUa?  sp.  No.  3. 
6a.  Exterior  of  a  dorsal  valve  from  Locality  311y,  Middle?  Cambrian  drift  bowlder  at  Ytternas,  Aland  Island, 
Finland.  Specimen  in  the  collection  of  the  ITniversity  of  L'psala,  Sweden;  cast  in  the  United  States 
National  Museum  (Cat.  No.  57094a).  Type  specimen,  figured  by  Wiman  [1902,  PI.  II,  fig.  35]  as 
LinguleUa?  sp.  No.  5. 

Obolus  (Westonia)  balticus  Walcott   (p.  453). 

Figure  7.  Partly  exfoliated  ventral  valve  from  Locality  311t,  Middle?  Cambrian  drift  bowlder  at  Ofverby,  Aland 
Island,  Finland.  Specimen  in  the  collection  of  the  University  of  Upsala,  Sweden;  cast  in  the  L'nited 
States  National  Museum  (Cat.  No.  57095a).  Specimen  figured  by  Wiman  [1902,  PI.  II,  fig.  34]  as 
LinguleUa?  sp.  No.  6. 

7a.  Dorsal  valve  from  Locality  311o,  Middle?  Cambrian  drift  bowlder  on  Skalstenarne  Island,  Gefle  Bay, 
Sweden.  Specimen  in  the  collection  of  the  University  of  Upsala,  Sweden;  cast  in  the  United  States 
National  Museum  (Cat.  No.  57090a).  Specimen  figured  by  Wiman  [1902,  PI.  II,  fig.  37]  as  LinguleUa? 
sp.  No.  4. 

7b.  Dorsal  valve  from  Locality  311h,  Middle?  Cambrian  drift  bowlder  No.  26,  on  Biludden,  Gefle  Bay, 
Sweden.  Specimen  in  the  collection  of  the  University  of  Upsala,  Sweden;  cast  in  the  United  States 
National  Museum  (Cat.  No.  57097a).  Type  specimen,  figured  by  Wiman  [1902,  PI.  II,  fig.  3S]  as 
LinguleUa?  sp.  No.  4. 


PLATE    XLIX. 


159 


PLATE  XLIX. 


a.  Central  lateral  space  of  area. 

c.  Trapezoidal  area,  including  central,  middle 

lateral,  and  outside  lateral  muscle  scars, 
h.  Central  muscle  scar, 
i.  Transmedian  muscle  scar. 
j.  Anterior  lateral  muscle  scar. 


k.  Middle  lateral  muscle  scar. 
1.  Outside  lateral  muscle  scar. 
p.  Pedicle  groove. 
V.  Visceral  cavity, 
vs.  Main  vascular  sinus. 
X.  Heart-shaped  cavity. 


Obolus  (Westonia)  escasoni  (Matthew)   (p.  459). 

Figure  1.  Cast  of  the  interior  of  a  ventral  valve,  showing  continuation  of  cast  of  pedicle  furrow,  with  the  central 

depres.sion  of  the  \'isceral  area.     University  of  Toronto,  Canada, 
la.  Interior  of  ventral  valve,  showing  heart-shaped  ca\'ity  and  position  of  central  muscle  scars;  also  a  strongly 

pitted  and  striated  interior  surface.     University  of  Toronto,  Canada.     Type  specimen,  figured  by 

Matthew  [1901a,  PI.  V,  fig.  Ig]  as  Lingulella  if)  escasoni. 
laa.  Enlargement  of  the  central  portion  of  figure  la  to  show  the  position  and  size  of  the  muscle  scars,  surface 

pits.  etc. 
lb.  Cast  of  the  inteiior  of  a  rather  large  dorsal  valve.     University  of  Toronto,  Canada.     Specimen  is  probably 

the  one  illustrated  Ijy  Matthew  [1901a,  PI.  V,  fig.  Id]  as  Lingulella  (f)  escasoni. 
Ic.  Id,  and  le.  Interior  of  dorsal  valves,  showing  the  position,  of  muscle  scars.     University  of  Toronto,  Canada. 
If.  Enlargement  of  the  exterior  surface  of  a  shell  3  mm.  long,  to  show  radiating  strise,  lines  of  growth,  and 

transverse  undulating  lines.     University  of  Toronto,  Canada. 

The  figiues  are  all  drawn  from  specimens  in  Matthew's  figured  material,  but  except  in  the  cases  noted  (figs,  la 
and  lb)  identification  is  impossible.  The  specimens  represented  are  all  from  Locality  325,  Upper  Cambrian  shales  on 
McAdam  Shore,  East  Bay,  Cape  Breton,  Nova  Scotia. 

Obolus  (Westoxia)  stoneanus  (Whitfield)   (p.  465). 

(PI.  XXVIII,  flgs.  2,2a-g.l 

Figure  2.  A  dorsal  valve  from  Locality  lie,  Upper  Camlwian  sandstone  near  Newton.  New  Jersey. 
2a.  Enlargement  of  the  exterior  surface  of  the  specimen  represented  by  figure  2. 

The  specimen  represented  was  figiu'ed  by  Weller  [1903,  PI.  I,  fig.  6]  as  Lingulella  stoneana. 

Lingulella  texana  Walcott  (p.  535). 

Figure  3.  Partly  exfoliaoed  doi-sal  valve,  showing  strong  radiating  striae  which  characterize  the  species.  Locality 
69,  LTpper  Cambrian  limestone  near  Honey  Creek,  Burnet  County,  Texas.  U.  S.  Nat.  Mus.  Cat. 
No.  .51805a. 
3a.  Cast  of  a  dorsal  valve,  the  iype  specimen,  showing  the  area  and  muscle  scars.  Locality  70,  Upper  Cam- 
brian limestone  near  Morgans  Creek,  Burnet  County,  Texas.  U.  S.  Nat.  Mus.  Cat.  No.  51806a.  Copied 
from  Walcott  [1908d.  PI.  VIII,  fig.  5]. 

Obolus  (Westonia)  iphis  Walcott   (p.  462). 

Figures  4  and  4'.  Ventral  \al\e  from  which  the  outer  layer  of  shell  has  been  exfoliated.  Locality  64,  Upper  Cam- 
brian limestone  near  llie  Bullwhacker  mine.  Eureka  district,  Nevada.  V.  S.  Nat.  Mus.  Cat.  No. 
51720a. 

4a  and  4a'.  Partly  exfoliated  dorsal  valve  from  Locality  201a,  Lower  Ordov-ician  limestone  east  of  Ham- 
burg Ridge,  Eureka  district,  Nevada.     L'.  S.  Nat.  Mus.  Cat.  No.  51542a. 

4b.  Dorsal  vahe  preserving  most  of  the  outer  layer  of  the  shell,  the  type  specimen,  associated  with  the 
shell  represented  by  figure  4a.     U.  S.  Nat.  Mus.  Cat.  No.  51542b. 

4c.  Dorsal  valve  associated  with  the  shell  represented  by  figure  4.     U.  S.  Nat.  Mus.  Cat.  No.  51720b. 

4d.  Enlargement  of  a  portion  of  the  outer  surface  of  the  shell  represented  in  figure  4b.     U.  S.  Nat.  MiLt. 
Cat.  No.  51-542b. 
160 


U.  S.   GEOLOGICAL  SURVEY 


MONOGRAPH   LI     PL.  XLIX 


FRANCE6  WIESER  0£L. 


PLATE  XLIX  161 

Obolus  (Westonia)  wasatchensis  Walcott  (p.  466). 

[Text  figs.  41A~F,  p.  407.] 

Figure  5.  Compressed  and  crushed  ventral  valve.     U.  S.  Nat.  Mum.  Cat.  No.  57098a. 

5a.  Dorsal  valve  flattened  in  the  siliceous  shale.     U.  S.  Nat.  Mus.  Cat.  No.  57098b. 

The  specimens  represented  are  both  from  Locality  32x,  Middle  Oambrian  shale  in  Wasatch  Canyon,  Boxelder 
County,  Utah. 

Obolus  (Westonua.)  ella  onaquiensis  Walcott  (p.  459). 

Figure  6.  Compressed,  exfoliated  dorsal  valve,  the  type  specimen.     U.  S.  Nat.  Mus.  Cat.  No.  51716a. 

6a.  Enlargement  of  the  surface  of  another  specimen  to  show  the  zigzag,  transverse  strise.     U.  S.  Nat.  Mus. 
Cat.  No.  51716b. 

The  specimens  represented  are  both  from  Locality  33f,  Middle  Cambrian  shales,  Onaqui  Range.  Tooele  County, 
Utah. 

62667°— VOL  51,  pt  2—12 11 


PLATE   L. 


163 


PLATE   L. 


a.  Central  lateral  space  of  area, 
a'.  Outer  lateral  space  of  area. 

b.  Bo.vS  (see  text  description,  p.  .571). 

c.  Trapezoidal  area,  including  central,  middle 

lateral,  and  outside  lateral  muscle  scars, 
f.  Flexure  line  of  area. 
Umbonal  muscle  scar. 
Central  muscle  scar. 


h. 


i.  Transmedian  muscle  scar. 


j.  Anterior  lateral  muscle  scar. 

k.  Middle  lateral  muscle  scar. 

1.  Outside  lateral  muscle  scar, 
mr.  Median  ridge. 

p.  Pedicle  groove, 
ps.  Parietal  band. 

s.  Median  septum, 
vs.  Main  vascular  sinus. 

X.  Heart-shaped  cavity. 


BiciA  GEMMA  (Billings)  (p.  569). 

Figures  1  aud  lb.  Exterior  and   side  view  of  a  ventral  valve  with  the  outer  siu'faee   parlly  removed  by  erosion. 

Locality  27,  Lower  Cambrian  limestone  near  Troy,  Rensselaer  County,  New  York.     U.  S.  Nat.  Mus. 

Cat.  No.  15349a. 
la.  Exterior  of  a  ventral  valve  associated  with  the  specimen  represented  by  figure  1,  preserving  the  interrupted 

radiating  stride  of  the  outer  surface.     U.  S.  Nat.  Mus.  Cat.  No.  15349b. 
Ic  and  Ic'.  Exterior  of  two  dorsal  valves,  associated  with  the  specimen  represented  by  figure  1.     L'.  S. 

Nat.  Mus.  Cat.  Nos.  lo349c  and  15349d,  respectively.     Specimen  figured  by  Walcott  [1886b,  PI.  X, 

fig.  2e]  as  Obolella  gemma. 
Id.  Posterior  portion  of  a  ventral  valve  associated  with  the  shell  represented  by  figure  1.  on  which  the  con- 
centric and  radiating  lines  are  very  strong  (.«ee  fig.  le).     U.  S.  Nat.  Mus.  Cat.  No.  15349e. 
le.  Outer  surface  of  a  ventral  vah'e  from  Locality  2b,  Lower  Cambrian  limestone  near  Beman  Park,  Troy, 

New  York,  greatly  enlarged.     This  may  possibly  be  the  surface  of  Bicia  U'hitearesi.     V.  S.  Nat.  Mus. 

Cat.  No.  51900a. 
If.  Natiu'al  cast  of  interior  of  ventral  vahe  from  Locality  2o,  Lower  Cambrian  limestone  bowlders  at  east 

entrance  to  Bic  Harbor,  Quebec.     U.  S.  Nat.  Mus.  Cat.  No.  14889d. 
Ig.  Nattrral  cast  of  interior  of  ventral  valve  associated  with  the  specimen  represented  by  figure  le,  at  Troy, 

New  York.     L'.  S.  Nat.  Mus.  Cat.  No.  51900b.     .\nother  specimen  (Cat.  No.  51900c)  was  used  to  aid 

in  restoring  certain  portions  of  this  figure. 
Ih,  li,  and  Ik.  Interiors  of  ventral  valves  showing  variation  in  area,  thickening  of  shell,  etc.     They  are 

associated  with  the  specimen  represented  by  figure  If,  at  Bic  Harbor,  Canada.     L'.  S.  Nat.  Mus.  Cat. 

Nos.  14S89C,  148S91),  and  14889a,  respectively.     The  specimens  represented  by  figures  li  and  Ik  were 

illustrated  by  Walcott  [188Gb,  PI.  X,  figs.  2b  and  2d.  respectively]  as  Ohohlla  getnma.     The  specimen 

illustrated  by  Walcott  [1886b,  PL  X,  fig.  2]  is  not  figured  in  this  monograph. 
Ij.  Interior  of  ventral  valve,  with  thick  shell  growth,  from  Locality  27,  Lower  Cambrian  limestone  near 

Tro)',  New  York.     U.  S.  Nat.  Mus.  Cat.  No.  1.5349e.     Specimen  figured  by  Walcott  [1886b,  PI.  X, 

fig.  2c]  as  Obolella  gemma. 
11.  Natural  cast  of  a  distorted  dorsal  valve  associated  with  the  specimen  represented  by  figure  le,  at  Troy, 

New  York.     U.  S.  Nat.  Mus.  Cat.  No.  51900d. 
Im.  Interior  of  a  dorsal  valve  associated  with  the  .'ihcll  represented  by  figure  If  at  Bic  Harbor,  Canada.     V.S. 

Nat.  Mus.  Cat.  No.  14889f. 
In.   Interior  of  dorsal  valve  from  Locality  2b,  Lower  Cambrian  limestone  near  Beman  Park,  Troy,  New  York. 

U.  S.  Nat.  Mus.  Cat.  No.  51900e.     This  drawing  is  based  on  one  fairly  well  preserved  interior,  but 

the  anterior  lateral  muscle  scars  and  some  other  details  arc  taken  from  five  other  associated  specimens 

(Cat.  Nos.  D1900f-i). 

BiciA  WHiTEAVESi  Walcott  (p.  570). 

Figures  2,  2a,  and  2b.  Interiors  of  ventral  valves,  showing  transition  from  short  form  of  ventral  valve  of  B.  gemma, 
figure  Ik,  to  the  typical  ventral  vaWe  of  B.  uhilearrni,  figure  2c.  U.  S.  Nat.  Mus.  Cat.  Nos.  35260a, 
3.5260b.  and  3.5260c,  respectively. 

2c.  Interior  of  a  ventral  valve,  the  type  specimen.     L'.  S.  Nat.  Mus.  Cat.  No.  35260d. 

2d,  Natural  cast  of  the  interior  of  the  specimen  represented  by  figure  2c.     U.  S.  Nat.  Mus.  Cat.  No.  35260e. 

2e.  Interior  of  a  dorsal  valve.     U.  S.  Nat.  Mus.  Cat.  No.  35260f. 

The  specimens  represented  are  all  from  Locality  2b.  Lower  Cambrian  limestone  near  Beman  Park,  Troy.  New 


York. 


164 


U.  S.   GEOLOGICAL  SURVEY 


MONOGRAPH   LI     PL.   L 


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.♦>   r'\ 


■  V  vs 


K  >> 


4 

r^' 


2" 

FRANCES  W1E8ER  OEL. 


V  VS 


HELIOTYPE  CO.,  BOSTON. 


PLATE   LI. 


165 


PLATE  LI. 


I.  Flexure  lines. 
h.  Central  muscle  scar, 
i.  Transmedian  muscle  scar, 
j.  Anterior  lateral  muscle  scar. 
1.  Outside  lateral  muscle  scar, 
p.  Pedicle  groove, 
r.  Area  of  posterior  adductor  scar. 


r'.  Areaof  anterior  adductor  scar 
s.  Median  septum. 
V.  Visceral  cavity, 
vs.  Vascular  sinus. 

ivs.  Central  lateral  branches  of  vascular 
system. 
X.  Ifeart-shaped  cavity. 


Elkania  desiderata  (Billings)  (p.  562) 


Figure  1.  Interior  of  a  ventral  valve,  showing  reversed  area  and  muscle  scars.     U.  S.  Nat.  Mas.  Cat.  No.  51943a. 
la.  Cast  of  interior  of  a  ventral  valve.     U.  S.  Nat.  Mus.  Cat.  No.  51943b. 
lb.  Cast  of  interior  of  dorsal  valve,  showing  main  vascular  sinuses  with  branches  extended  over  central  area. 

U.  S.  Nat.  Mus.  Cat.  No.  51943c. 
Ic.  Cast  of  interior  of  dorsal  valve,  showing  central  area  defined,  b"ut  no  traces  of  branches  of  main  vascular 

sinuses.     This  central  area  has  been  interpreted  as  probably  the  area  of  attachment  of  muscles,  by 

authors  who  have  written  of  the  species.     IT.  S.  Nat.  Mus.  Cat.  No.  51943d. 
Id.  Cast  of  interior  of  a  dorsal  valve  in  which  the  \dsceral  area  is  beautifully  defined,  but  the  vascular  sinuses 

and  the  central  area  included  within  them  are  not  defined.     U.  S.  Nat.  Mus.  Cat.  No.  51943e. 

The  specimens  represented  are  all  from  Locality  319a,  Lower  Ordovician  shales,  at  Point  Levis,  Quebec. 

Elkania  ambigua  (Walcott)  (p.  562). 

Figure  2.  Exterior  of  ventral  valve.  This  specimen  can  not  he  located  and  the  locality  number  Ls  not  known.  The 
figure,  however,  is  a  new  drawing  of  the  specimen  illustrated  by  \Valcott  [1884b,  PI.  I,  fig.  2b]  as 
Obolellaf  ambigua. 

2a.  Partly  exfoliated  dorsal  valve,  showing  the  outlines  of  the  visceral  area  and  main  vascular  sinuses  on 
the  inner  laraellations  of  the  shell.  U.  S.  Nat.  Mus.  Cat.  No.  24554a.  Type  specimen,  figured  by 
Walcott  [1884b,  PI.  I,  fig.  2a]  as  Obolellaf  amUgua. 

2b.  Interior  of  a  dorsal  valve,  showing  visceral  area,  muscle  scars,  and  main  vascular  sinuses.  U.  S.  Nat.  Mus. 
Cat.  No.  24554b.     Specimen  figured  by  Walcott  [1884b,  PI.  I,  fig.  2c]  as  Obolella  f  ambigua. 

2c.  Cast  of  the  interior  of  a  dorsal  valve  in  which  the  thickening  of  the  shell  within  the  lines  of  the  main  vascu- 
lar sinuses  is  greater  than  in  any  other  specimen.  The  visceral  area  also  extends  farther  forward 
into  the  valve.  This  variation  in  the  forward  extension  of  the  visceral  area  is  not  infrequent  in 
species  of  Obolus.     U.  S.  Nat.  Mus.  Cat.  No.  24554c, 

The  specimens  represented  by  figures  2a-c  are  all  from  Locality  63,  Lower  Ordo\-ician  limestone,  northeast  of 
Adams  Hill,  Eureka  district,  Nevada. 

Obolus  (Fordinia)  bellulus  (Walcott)  (p.  428). 

Figure  3.  Top  and  side  views  of  a  partly  exfoliated  ventral  valve  from  Locality  7z,  Upper  Cambrian  limestone, 
about  3  miles  southeast  of  Emigrant  Pa.ss,  Esmeralda  County,  Nevada.  U.  S,  Nat.  Mus.  Cat.  No. 
51944g. 

3a.  Interior  of  a  ventral  valve,  the  type  specimen,  showing  central  trapezoidal  area  at  x;  also  main  vascular 
sinuses,  pedicle  groove,  etc.     IT.  S,  Nat.  Mus,  Cat,  No,  51944a. 

3b  and  3c.  Caat.s  of  interior  of  ventral  valves.     V.  S.  Nat.  Mus.  Cat,  Nos,  51944b  and  51944c,  respectively. 

3d.  Partly  exfoliated  dorsal  valve.     U.  S.  Nat.  Mus.  Cat.  No.  51944d. 

3e.  Interior  of  dorsal  valve.     U.  S.  Nat.  Mus.  Cat.  No,  51944c. 

3f.  Cast  of  interior  of  dorsal  valve.     U.  S.  Nat.  Mus.  Cat.  No.  51944f. 

The  specimens  represented  by  figures  3a-f  are  from  Locality  7x,  Upper  Cambrian  limestones  about  2.5  miles 
southeast  of  Emigrant  Pass,  Silver  Peak  quadrangle,  Esmeralda  County,  Nevada. 
166 


U.   S.   GEOLOGICAL  SURVEY 


MONOGRAPH   LI     PL,  LI 


'   r 


J^^^k 

nN 

/I 

Jf^S/ki^ 

K   \ 

/ 

^    1 

i'      v/ 

f 

vl 

FRANCES  WIE8ER  DEL. 


MELtOTYPE   CO   ecSTON 


PLATE  LI.  167 

Elkania  IDA  (Billings)  (p.  563). 

[PI.  XXX,  figs.  20  and  20a.] 

Figures  4  and  4a.  Top  and  side  views  of  a  partly  exfoliated  ventral  valve.     Geol.  Survey  Canada. 

4b.  Cast  of  the  interior  of  a  dorsal  valve,  showing  elevated  visceral  cavity  and  muscle  scars.     Geol.  Survey 

Canada. 
4c.  Interior  of  a  ventral  valve,  preserving  a  portion  of  the  reversed  area.     Geol.  Survey  Canada. 

The  specimens  represented  are  all  from  Locality  3191.  limestone  No.  2  of  Billings's  section,  at  Point  LevLs,  Qncbec. 
Obolus  (Fordinia)  gilberti  Walcott  (j).  429). 

Figures  5,  5a,  and  5c.  Side  and  top  views  of  ventral  valves  varying  in  outline  and  convexity.     U.  S.  Nat.  Mus.  Cat. 

Nos.  5194f)a,  51946c,  and  51946d,  respectively.     Figure  5,  the  type  specimen,  is  copied  from  Walcott 

[1908d,  PI.  VII,  tig.  16]. 
5b.  Interior  of  dorsal  valve.     U.  S.  Nat.  Mus.  Cat.  No.  5194(ib.     Copied  from  Walcott  [1908d,  PI.  VII,  fig.  15a]. 
5d.  Exterior  of  dorsal  valve.     U.  S.  Nat.  Mus.  Cat.  No.  5194Ge. 

The  specimens  represented  are  all  from  Locality  lln.  Middle  Cambrian  limestone  southeast  of  Marjum  Pass. 
House  Range,  Utah. 

Schuchertina  CAMBRIA  Walcott  (p.  5S5). 

Figures  (i,  6',  and  6".  Exterior,  side,  and  back  views  of  a  partly  exfoliated  ventral  valve.     U.  S.  Nat.  Mus.  Cat. 

No.  51411a. 
6a.  Exterior  of  a  large,  partly  exfoliated  ventral  valve  with  a  slight  median  fold.     U.  S.  Nat.  Mus.  Cat.  No. 

51411b. 
6b.  Cast  of  the  interior  of  a  ventral  valve,  the  type  specimen,  showing  flabelliform  muscle  scars.     V.  S.  Nat. 

Mus.  Cat,  No.  51411c. 
6c.  Interior  of  the  ventral  valve  represented  l3y  figure  61),  drawn  from  a  cast  of  that  specimen.     U.  S.  Nat. 

Mus.  Cat.  No.  51411c.     Parts  of  this  figure  are  restored  from  other  specimens. 
6d  and  6d'.  Top,  back,  and  side  views  of  a  cast  of  the  interior  of  a  slightly  distorted  ventral  valve.     IT.  S. 

Nat.  Mus.  Cat.  No.  51411d. 
6e.  Interior  of  the  ventral  valve  represented  by  figure  6d,  obtained  by  making  a  cast  of  that  specimen.     U.  S. 

Nat.  Mus.  Cat.  No.  51411d. 
6f.  Top  and  side  view  of  a  cast  of  a  dorsal  valve.     U.  S.  Nat.  Mus.  Cat.  No.  51411e. 
6g.  Exterior  of  a  dorsal  valve.     U.  S.  Nat.  Mus.  Cat.  No.  51411f. 
6h.  Cast  of  the  interior  of  a  ventral  valve.     U.  S.  Nat.  Mus.  Cat.  No.  51411g. 
6i.  Interior  of  tlie  ventral  valve  represented  by  figure  6h  obtained  by  making  a  cast  of  that  specimen.     U.  S. 

Nat.  Mus.  Cat.  No.  5141  Ig. 
6]'.  Cast  of  the  interior  of  a  dorsal  valve,  showing  mesial  area  and  va.scular  markings.     U.  S.  Nat.  Mus.  Cat. 

No.  51411h. 
6k.  Enlargement  of  the  central  portion  of  figure  6j. 

6  1.  Cast  of  the  posterior  portion  of  the  interior  of  a  dorsal  valve.     U.  S.  Nat.  Mus.  Cat.  No.  514111. 
6m.  Interior  of  the  posterior  portion  of  the  dorsal  valve  represented  by  figure  6  1,  obtained  by  making  a  cast 

of  that  specimen.     U.  S.  Nat.  Mus.  Cat.  No.  514111. 

The  specimens  represented  by  figures  6,  6a-m  are  from  Locality  5k.  Middle  Cambrian  limestones  on  the  road  to 
Wolsey,  about  8  miles  south  of  Neihart.  Little  Belt  Mountains,  Montana. 


PLATE    LII. 


169 


PLATE  IJI. 

a.  Area  of  dorsal  valve.  sh.  Cast  of  exterior  of  cardinal  area  on  eafh  side 
cl.  Cardinal  muscle  scar.  ot  pedicle  furrow, 

h.  Central  scars.  v.  Visceral  area, 

p.  Cast  of  pedicle  groove.  vs.  Main  vascular  sinus, 
s.  Median  septum. 

DiCELLOMUS   POLITUS    (Hall)    (]).  575). 

[Text  figs.  ICA-B,  p.  314,  and  49A-B,  p.  57C.] 

Figure  1.  Ventral  valvo.     Thospe.cLmenfrom  which  this  figure  was  drawn  can  not  now  be  located.     The  locality  and 

catalogue  number  are  therefore  unknown. 
la.  Ventral  valve  from  Locality  98,  Upper  Cambrian  sandstone  at  Eau  Claire,  Wisconsin.     U.  S.  Nat.  Mua. 

Cat.  No.  35211a. 
lb.  Exterior  and  side  views  of  ventral  valve  from  Locality  78a,  Upper  Cambrian  sandstone  on  Mount  Wash- 
ington, near  Eau  Claire,  Wisconsin.     U.  S.  Nat.  Mus.  Cat.  No.  27447a. 
Ic  and  Id.  Casts  of  interiors  of  ventral  valves  associated  with  the  shell  represented  by  figure  la.     V.  S.  Nat. 

Mus.  Cat.  Nos.  3.5211b  and  3.5211c,  respectively.    The  specimen  represented  byfigtire  Ic  was  figured 

by  Walcott  [1899,  PI.  LX,  fig.  4a]. 
le.  Partly  exfoliated  ventral  valve  in  which  the  visceral  area  extends  forward  of  the  center  of  the  valve. 

Locality  82b,  Upper  Cambrian  sandstone  near  Taylors  Falls,  Miimesota.     U.  S.  Nat.  Mus.  Cat. 

No.  51916a. 
If.  Dorsal  valve  associated  with  the  shell  represented  by  figure  le.     U.  S.  Nat.  Mus.  Cat.  No.  5191Gb. 
Ig  and  Ih.  Exteriors  and  side  outlines  of  dorsal  A-alves  associated  with  the  shell  represented  by  figure  la. 

U.  S.  Nat.  Mus.  Cat.  Nos.  35211d  and  3.5211e,  respectively. 
li.  Interior  of  a  ventral  \alve,  associated  with  the  shell  represented  by  figure  la,  showing  excavated  area  on 

each  side  of  the  median  line  of  the  flattened  posterior  margin.     U.  S.  Nat.  Mus.  Cat.  No.  35211f. 
Ij.  Interior  of  a  ventral  valve,  associated  with  the  shell  represented  by  figure  la,  showing  large  composite 

muscle  scars  (cl),  median  septum  (s),  vascular  sinuses  (vs),  and  area.     U.  S.  Nat.  Mus.  Cat.  No.  3.5211g. 

Specimen  figured  by  Walcott  [1899,  PL  LX,  fig.  4]. 
Ik.  Cast  of  interior  of  a  dorsal  valve  associated  with  the  shell  represented  by  figure  la.    1^.  S.  Nat.  Mus.  Cat. 

No.  3.521  Ih. 
2  and  2a.  Partly   exfoliated  ventral  valves  from    Locality   3S5e,  Upper  Cambrian  sandstone.  Black  Hills, 

South  Dakota.     U.  S.  Nat.  Mus.  Cat.  Nos.  51924a  and  51924b,  respectively. 
2b.  Partly  exfoliated  ventral  valve  from  Locality  167.  Middle  Cambrian   sandstone  9  miles  west  of  Custer, 

Black  Hills,  South  Dakota.     U.  S.  Nat.  Mus.  Cat.  No.  51919a. 
2c.  Partly  exfoliated  dor.sal  valve  associated  with  the  shells  represented  by  figures  2  and  2a.     L'.  S.  Nat. 

Mus.  Cat.  No.  51924c. 
2d,  2e,  and  2f.  Partly  exfoliated  dorsal  valves  associated  with  the  shell  represented   by  figure  2b.     U.  S. 

Nat.  Mus.  Cat.  Nos.  51919b,  51919c,  and  51919d.  respectively. 
2g.  Exterior  of  a  ventral  valve  from  Locality  356,  Middle  Cambrian  sandstones  on  Red  Canyon  Creek,  Black 

Hills,  South  Dakota.     U.  S.  Nat.  Mus.  Cat.  No.  24593a.     Specimen  figured  by  Whitfield  [1880,  PI.  II, 

fig.  13]  as  Oholella  polita.     The  specimen  represented  by  figure  12  of  Whitfield's  paper  is  not  figured 

in  this  monograph. 
2h.  Ventral  valve  from  Locality  35Se,  L'pper  Cambrian  sandstone.  Black  Hills,  South  Dakota.     U.  S.  Nat. 

Mus.  Cat.  No.  1027a.     Specimen  figured  by  Meek  and  Hayden  [1865,  PI.  I,  figs.  2a-b]  as  Linffidepis 

prima. 
21.   Dorsal  valve  associated  with  the  ventral  valve  represented  by  figure  2h.     U.  S.  Nat.  Mus.  Cat.  No.  1027b. 

3.  Partly  exfoliated  dorsal  valve,  from  Locality  302k.  Middle  Cambrian  limestones,  near  Gallatin,  Montana. 

U.  S.  Nat.  Mus.  Cat.  No.  51923a. 

4.  Ventral  valve,  broadened  by  distortion  and  partly  exfoliated.     U.  S.  Nat.  Mus.  Cat.  No.  51913a. 
4a.  Dorsal  valve,  broadened  by  distortion.    U.  S.  Nat.  Mus.  Cat.  No.  51913b. 

The  specimens  represented  by  figures  4  and  4a  are  both  from  Locality  302s,  Middle  Cambrian  shale  1.5  miles 
eoutb  of  Helena,  Montana.    They  are  somewhat  doubtfully  referred  to  this  species. 

Figure  5.  Partly  exfoliated  ventral  valve.     U.  S.  Nat.  Mus.  Cat.  No.  51921a. 

5a.  Exterior  view  and  side  outline  of  dorsal  valve.     U.  S.  Nat.  Mus.  Cat.  No.  51921b. 
5b.  Fragment  of  cast  of  interior  of  a  <lorsal  valve.    U.  S.  Nat.  Mus.  Cat.  No.  51921c. 

The  specimens  represented  by  figures  5,  5a-b  are  all  from  Locality  329b,  Middle  Cambrian  limestone,  collected 
by  the  Wheeler  Survey  in  Utah. 
170 


U.  S.   GEOLOGICAL  SURVEY 


MONOGRAPH   LI     PL.  Lll 


fRANCES  WIESEH  DEL. 


KGl-IOTVPE    CO   B3STOI* 


PLATE  LII.  171 

DiCELLOMUS    PECTENOIDES    (Wllitfield)     (]).  575    . 
[Textflgs.  48A-B,p.  575.] 

Figure  6.  A  transverse,  partly  exfoliated  ventral  valve  from  Locality  35Sb,  Middle  Cambnan  sandstone  on  Castle 

Creek,  Black  Hills,  South  Dakota.     U.  S.  Nat.  Mua.  Cat.  No.  24592a.     Specimen  figured  by  Whif^ 

field  [ISSO,  PI.  II,  fig.  18]  as  Obolus?  pecterioides.    This  may  be  the  type  specimen,  but  it  can  not 

be  identified  with  any  of  Whitfield's  figures  [1875,  unnumbered  plate,  figs.  1-3]. 

6a.   Partly  exfoliated  dorsal  valve  associated  with  the  shell  represented  by  figure  6.     U.  S.  Nat.  Mus.  Cat 

No.  24.592b.     Specimen  figured  by  Whitfield  [1880,  PI.  II,  fig.  19]  as  Obolus  f  pectenoides. 
6b.  Cast  of  interior  of  a  ventral  valve  from  Locality  164,  Middle  Cambrian  sandstone  near  Deadwood,  Black 
Hills,  South  Dakota.     U.  S.  Nat.  Mus.  Cat.  No.  51911a. 

6c.  Cast  of  interior  of  a  dorsal  valve  associated  with  the  shell  represented  by  figure  6b      U   S    Nat   Mus 'Cat 
No.  51911b.  ■ ' 

DiCELLOMUS  sp.  undt.  Walcott   (p.  578). 

FiGDREs  7  and  7a.  Exterior  and  side  views  of  a  dorsal  valve,  from  Locality  3101,  Middle  Cambrian  at  Andrarum, 
Pro\dnee  of  Christianstad,  Sweden.     U.  S.  Nat.  Mus.  Cat.  No.  58304. 


PLATE    LIII. 


173 


PLATE  LIII. 


c.  Trapezoidal  arta,  including  central, 
middle  lateral,  and  outside  lateral 
muscle  scars. 

el.  Cardinal  scars. 

h.  Central  muscle  scar. 

i.    Transmcdian  muscle  scar. 


j.  Anterior  lateral  muscle  scar. 
k.  Middle  lateral  muscle  scar. 
1.  Outside  lateral  muscle  scar, 
p.  Pedicle  furrow. 
V.  Visceral  area. 
vs.  Vascular  sinus. 


DiCELLOMUs  NANUS  (Meek  and  Hayden)  (p.  573). 

Figures  1  and  la.  Exterior  and  side  views  of  ventral  valves  varying  in  outline.     U.  S.  Nat.  Mus.  Cat.  Nos.  51903in 
and  51903a,  respectively, 
lb.  Interior  of  a  ventral  valve.     U.  S.  Nat.  Mus.  Cat.  No.  51903b. 
Ic.  Natural  cast  of  an  interior  of  a  ventral  valve.     U.  S.  Nat.  Mus.  Cat.  No.  51903c. 
Id.  Interior  of  a  ventral  valve.     U.  S.  Nat.  Mus.  Cat.  No.  51903d. 
le.  Natural  cast  of  an  interior  of  a  ventral  valve.     U.  S.  Nat.  Mus.  Cat.  No.  51903e. 
If.  Partly  exfoliated  ventral  valve.     U.  S.  Nat.  Mus.  Cat.  No.  51903f. 
Ig  and  Ih.  Exterior  and  side  views  of  dorsal  valves  varying  in  outline.     V.  S.  Nat.  Mus.  Cat.  Nos.  51903g 

and  51903h,  respectively, 
li.  Interior  of  a  dorsal  valve.     U.  S.  Nat.  Mus.  Cat.  No.  519031. 
Ij.  Natural  cast  of  interior  of  a  dorsal  valve.     U.  S.  Nat.  Mus.  Cat.  No.  51903J. 

Ik.  Natural  cast  of  interior  of  a  dorsal  valve  with  large  cardinal  scars.     TJ.  S.  Nat.  Mus.  Cat.  No.  519031i. 
1 1.  Interior  of  a  dorsal  valve  showing  area.     U.  S.  Nat.  Mus.  Cat.  No.  519031. 

The  specimens  represented  by  figures  1,  la-1  are  from  Locality  170,  Middle  Cambrian  limestone  about  10  miles 
south-southeast  of  Bald  Mountain,  Bighorn  Mountains,  Wyoming. 

Figure  2.  Interior  of  a  ventral  valve  from  Locality  355d,  Upper  Cambrian  sandstone,  Black  Hills,  South  Dakota. 

U.  S.  Nat.  Mus.  Cat.  No.  1025a.     Type  specimen,  figured  by  Hayden  [1862,  fig.  2b,  p.  73]  as  Obolella 

nana,  and  by  Walcott  [1899,  PI.  LX,  fig.  3d]  as  Dicellomus  nanus. 
2a.  Partly  exfoliated  dorsal  valve  associated  with  the  shell  represented  by  figure  2.     U.  S.  Nat.  Mus.  Cat. 

No.  1025b.     Specimen  figured  by  Hayden  [1SG2,  fig.  2a,  p.  73]  as  Obolella  nana,  and  by  Walcott 

[1899,  PI.  LX,  fig.  3b]  as  Dicellomus  nanus. 
3.  Exfoliated  ventral  valve  from  Locality  152a,  Upper  Cambrian  sandstone  on  Dry  Creek,  Gallatin  County, 

Montana.     U.  S.  Nat.  Mus.  Cat.  No.  51908a. 
3a.  Natural  cast  of  an  interior  of  a  ventral  valve  from  Locality  170,  Middle  Cambrian  limestone  10  miles  south- 
southeast  of  Bald  Mountain,  Bighorn  Mountains,  Wyoming.     U.  S.  Nat.  Mus.  Cat.  No.  51903n. 
3b.  Dorsal  valve  associated  with  the  shell  represented  by  figure  3a.     U.  S.  Nat.  Mu.s.  Cat.  No.  51903o. 
3c  and  3d.  Exteriors  of  dorsal  valves  associated  with  the  shells  represented  by  figure  3.     U.  S.  Nat.  Mus.  Cat. 

Nos.  51908b  and  51908c,  respectively. 

Dicellomus  appalachia  Walcott  (p.  572). 

Figure  4.  Exterior  of  a  ventral  valve  from  Locality  119,  Middle  Cambrian  limestone  collected  somewhere  in  either 
Jefferson  or  Hawkins  County,  Tennessee.     V.  S.  Nat.  Mus.  Cat.  No.  51926a. 

4a.  Cast  of  interior  of  a  ventral  valve,  the  type  specimen,  from  Locality  89,  Middle  Cambrian  limestone  in 
Murphrees  Valley,  Blount  County,  Alabama.     U.  S.  Nat.  Mus.  Cat.  No.  51928a. 

4b.  Exterior  of  a  ventral  valve  from  Locality  90a,  Middle  Cambrian  shales  at  Cedar  Bluff,  Cherokee  County, 
Alabama.     U.  S.  Nat.  Mus.  Cat.  No.  51939a. 

4c.  Dor.sal  valve  from  Locality  16,  Middle  Cambrian  limestone  in  Blountsville  Valley,  Blount  County,  Ala- 
bama.    U.  S.  Nat.  Mus.  Cat.  No.  51937a. 

4d.  Partly  exfoliated  dorsal  valve  associated  with  the  shell  rei)resent«d  by  figure  4.     L^.  S.  Nat.  Mus.  Cat. 
No.  51926b. 

4e.  Partly  exfoliated  dorsal  valve,  as.sociated  with  the  shell  represented  by  figure  4a,  .showing  visceral  area, 
muscle  scars,  etc.     U.  S.  Nat.  Mus.  Cat.  No.  5192Sb. 

4f.  Partly  exfoliated   dorsal   valve,  from  Locality  91,  Middle  Cambrian  shales  at  Cedar  Bluff,  Cherokee 
County,  Alabama.     U.  S.  Nat.  Mus.  Cat.  No.  51936a. 

4g.  Partly  exfoliated  dorsal  valve  from  Locality  103a,  Middle  Cambrian  shale  on  the  road  from  Rogersville 
to  Dodson  Ford,  Hawkins  County,  Tennessee.     U.  S.  Nat.  Mus.  Cat.  No.  51938a. 
174 


U.  S.   GEOLOGICAL  SURVEY 


MONOGRAPH   LI     PL.  Llll 


\ 


cl         \ 


1/ 


HELiOTYPE  CO..  BOSTON, 


PLATE    LIV. 


175 


PLATE  LIV. 

a.  Central  lateral  space  of  area.  i.  Transmedhin  muscle  scar, 

a'.  Outer  lateral  space  of  area.  j.  ^Vnt<!rior  lateral  muscle  scar. 

c.  Trapezoidal  area,  including;  central,  1.  Outside  lateral  muscle  scar. 

middle  lateral,  and  outside  lateral  p.  Pedicle  groove. 

muscle  scars.  pc.  Cast  of  pedicle  opening, 

f.  Fle-vuro  line  of  area.  v.  Visceral  cavity, 

h.  Central  muscle  scar.  vs.  Main  vascular  sinus. 

Obolei.l.v  ciinoMATic.v  Billings  (p.  591). 

Figure  1.  Ventral  valvo  of  the  usual  form  and  oullinu.     U.  S.  Nat.  Mu.s.  Cat.  No.  14891a. 

la.  Posterior  view  of  the  speciihen  represented  by  figure  lb,  showing  area  and  narrow  pedicle  slh.  V.  S. 
Nat.  Mus.  Cat.  No.  14891b. 

lb  and  Ic.  Outer  and  side  view  of  a  ventral  valve  that  is  less  elongate  than  specimen  represented  by  figure  1 
(see  fig.  la).     U.  S.  Nat.  Mus.  Cat.  No.  14891b. 

Id.  Dorsal  valve,  in  which  the  structure  of  the  .shell  is  unusually  well  preserved.  U.  S.  Nat.  Mus.  Cat.  No. 
14891c. 

le.  Cast  in  limestone  of  the  interior  of  a  ventral  valve,  showing  vascular  markings  and  muscle  scars.  The 
extreme  posterior  portion  is,  unfortunately,  broken  away.  The  false  pedicle  furrow  is  too  deep  and 
strqng.     It  is  shallow  in  the  specimen.     U.  S.  Nat.  Mus.  Cat.  No.  14891d. 

If.  Interior  of  a  ventral  valve  that  has  a  narrow  thickening  of  the  shell  just  in  front  of  the  area,  corresponding 
to  the  posterior  portion  of  the  thickened  shell  usually  present  in  the  ventral  valve  of  ObokUa  aassa 
beneath  the  visceral  area.     (See  figs.  2g  and  2i.)    Geol.  Survey  Canada. 

Ig.  Cast  in  limestone  of  the  interior  of  a  small  dorsal  valve.     U.  S.  Nat.  Mus.  Cat.  No.  14891et 

Ih.  Interior  of  a  dorsal  valve.  The  area  is  outlined  from  a  specimen  in  the  collection  of  the  Geological  Sur- 
vey of  Canada.  U.  S.  Nat.  Mus.  Cat.  No.  14891f.  Specimen  figured  by  Walcott  [1886b,  PI.  XI, 
fig.  lb].  The  specimens  represented  by  figures  1  and  la  [AValcott,  1886b,  PI.  XI]  are  not  redrawn 
in  this  monograph. 

li.  Interior  of  a  dorsal  valve  drawn  from  a  plaster  cast  of  a  limestone  cast  in  the  collection  of  the  Geological 
Survey  of  Canada;  cast  in  the  United  States  National  Museum  (Cat.  No.  14891g).  Cast  figured  by 
Walcott  [1886b,  PI.  X,  fig.  3];  and  [1891a,  PI.  LXXI,  fig.  3]  as  OboleUa  circe. 

The  specimens  represented  by  figiuesl,  la-i  are  all  from  Locality  392a,  Lower  Cambrian  limestone  at  L'Anse  au 
Loup,  Straits  of  Belleisle,  Labrador.  The  material  in  the  collections  of  the  Geological  Survey  of  Canada  includes 
the  specimens  upon  which  Billings  founded  the  species,  but  closer  identification  is  impossible. 

Obolei.la  crassa   (Hall)   (p.  592). 

[Text  flg.  14,  p.  299.] 

Figure  2.  E.xterior  of  a  ventral  valve  of  the  usual  form  and  outline  from  Locality  27,  Lower  Cambrian  limestone  in 

the  eastern  suburb  of  Troy,  New  York.     V.  S.  Nat.  Mus.  Cat.  No.  15348a. 
2a.  An  unusually  elongate  ventral  valve,  with  the  surface  characters  well  preserved,  from  Locality  2b,  Lower 

Cambrian  limestone  just  north  of  Beman  Park,  Troy,  New  York.    U.  S.  Nat.  Mus.  Cat.  No.  51951a. 
2b.  An  unusually  broad  ventral  valve  associated  wath  the  shell  represented  by  figure  2a.     L^.  S.  Nat.  Mus. 

Cat.  No.  51951b. 
2c  and  2d.  Exterior  and  side  \-iews  of  a  dorsal  valve,  associated  with  the  shell  represented  by  figure  2a.     I".  S. 

Nat.  Mus.  Cat.  No.  51951c. 
2e.  Posterior  \-iew  of  a  vPntral  valve  associated  with  the  shell  represented  by  figure  2a,  showing  low  area  and 

the  pedicle  slit.     U.  S.  Nat.  Mus.  Cat.  No.  51951d. 
2f.  Section  of  a  ventral  valve  as.sociated  with  the  .shell  represented  by  figure  2a,  naturally  broken  near  the 

median  line.    The  thickest  part  of  the  shell  is  over  the  visceral  area.     U.  S.  Nat.  Mus.  Cat.  No. 

51951e. 
2g,  2h,  and  2i.  Interiors  of  ventral  valves  illustrating  variation  in  the  areas,  vascular  markings,  and  muscle 

scars.     Note  the  narrow  rounded  area  and  the  shallow  median  furrow  in  figure  2h;  the  inner  end  of 

the  pedicle  tube  is  shown  on  the  specimen  just  beneath  the  inner  edge  of  the  area.     Locality  2b, 

Lower  Cambrian  limestone  just  north  of  Beman  Park,  Troy,  New  York.     U.  S.  Nat.  Mus.  Cat.  Nos. 

51951f,  51951g,  and  51951h,  respectively. 
176 


U.  S.  GEOLOGICAL  SURVEY 


MONOGRAPH    LI     PL.  LIV 


FRANCES  WIESER  DEL. 


HCLtuTi/PE    CO   BOSTON 


PLATE  LIV.  177 

Obolella  crassa  (Hall) — Continued. 

Figure  2j.  Interior  of  ventral  valve  from  Locality  29a,  Lower  Cambrian  limestone  at  Sehodaek,  Rensselaer  County, 
New  York.     U.  S.  Nat.  Mus.  Cat.  No.  51952a. 

2k.  Interior  of  a  dorsal  valve  associated  with  the  specimen  represented  by  figiire  2a.  V.  S.  Nat.  Mus.  Cat. 
No.  519511. 

2  L  Cast  in  limestone  of  the  interior  of  a  dorsal  valve  from  Locality  27,  Lower  Cambrian  limcslone  in  the 
eastern  suburb  of  Tro>',  New  York.  The  exact  position  of  the  anterior  lateral  mu.sde  scars  in  figure 
2  1  is  more  or  less  uncertain  and  the  line  from  (i)  indicating  the  transmedian  scar  should  unite  wilh 
that  from  (1)  as  in  figure  2  1.  V.  S.  Nat.  Mus.  Cat.  No.  15347a.  Specimen  figured  by  WalcoU  [1886b, 
PL  X,  fig.  Ic].    The  other  specimens  illu.strated  [Walcott,  1886b]  are  not  redrawn  in  this  monograph. 

2m.  Interior  of  a  dorsal  valve  associated  with  the  specimen  represented  by  figure  2a.  The  other  specimens 
were  used  to  draw  in  the  details  of  the  area.     U.  S.  Nat.  Mus.  Cat.  No.  51951J. 

2n.  Cast  of  the  interior  of  a  ventral  valve  associated  with  the  shell  represented  by  figure  2a.  U.  S.  Nat.  Mus. 
Cat.  No.  51951k. 

Obolella  minor  (Walcott)   (p.  596). 

Figure  3.  Exterior  of  a  ventral  valve.     U.  S.  Nat.  Mus.  Cat.  No.  24628c. 

3a.  Cast  of  the  interior  of  a  ventral  valve,  the  type  specimen,  showing  area  and  cast  of  pedicle  groove.     U.  S. 

Nat.  Mus.  Cat.  No.  24628a. 
3b.  Cast  of  interior  of  ventral  valve.     U.  S.  Nat.  Mus.  Cat.  No.  24628d. 
3c.  Exterior  of  dorsal  valve.     U.  S.  Nat.  Mus.  Cat.  No.  24628b. 
3d.  Cast  of  interior  of  a  dorsal  valve.     U.  S.  Nat.  Mus.  Cat.  No.  24628e. 

The  specimens  represented  are  all  from  Locality  32,  Lower  Cambrian  sandstone,  Stis.sing  Mountain,  Dutchess 
County,  New  York.     The  figures  (3,  3a-d)  are  copied  from  Walcott  [lS91a,  PI.  LXXII,  figs.  4a,  4d,  4,  4b,  and  4c, 
respectively].     They  were  then  labeled  "  Camarella  f  minnr." 
62667°— VOL  51,  pt  2—12 12 


PLATE    LV. 


179 


PLATE  LV. 


a.  Central  lateral  space  o(  area, 
i.  Transmedian  muscle  scar, 
j.  Anterior  lateral  muscle  scar. 
1.  Outside  lateral  scar. 
p.  Pedicle  groove. 


pc.  Cast  of  pedicle  opening. 

s.  Median  septum. 

V.  Visceral  cavity, 
vs.  Main  vascular  sinus. 

.\.  Heart-shaped  cavity 


Ic. 


Id. 


le. 


Obolella  atlantica  Walcolt  (p.  589). 

(Text  fig.  51,  p.  aiil.l 

Figure  1.  Exterior  of  an  unusually  convex,  elongate  \entral  valve.     Locality  So,  Lower  Cambrian  siliceous  shale, 
Smith  Sound,  Trinity  Bay,  Newfoundland.     U.  S.  Nat.  Mus.  Cat.  No.  51948a. 

la.  Cast  in  siliceous  shale  of  the  exterior  of  a  ventral  valve,  showing  surface  characters  of  the  shell.  Same 
locality  as  specimen  represented  by  figure  1.     V.  S.  Nat.  Mus.  Cat.  No.  51948b. 

lb.  Exterior  of  a  small  ventral  ?  valve.     Locality  41a,  Lower  Cambrian  limestone  beneath  Topsail  Head, 
Conception  Bay,  Newfoundland.     U.  S.  Nat.  Mus.  Cat.  No.  56957a. 
Exterior  of  small  dorsal  valve,  associated  with  specimen  represented  by  figure  ll>.     U.  S.  Nat.  Mus.  Cat. 

No.  .5G957b. 
A  slightly  distorted  dorsal  valve  from  Locality  5o,  Lower  Cambrian  siliceous  shale,  Smith  Sound,  New- 
foundland. U.  S.  Nat.  Mus.  Cat.  No.  5194Sc. 
Interior  of  a  ventral  valve  associated  with  the  shell  represented  by  figiu-e  Id.  The  pedicle  furrow  is  too 
strong  in  the  figure.  On  the  specimen  it  is  indicated  by  a  slightly  depressed  line  on  each  side  of 
what  is  usually  the  pedicle  fuiTow.  This  specimen  i.s  also  figured  in  a  slightly  different  position  in 
text  figure  51,  p.  590.     U.  S.  Nat.  Mus.  Cat.  No.  51948d. 

If  and  Ig.  Casts  of  the  interior  of  ventral  valves  associated  with  the  shell  represented  by  figure  Id.  U.  S. 
Nat.  Mus.  Cat.  Nos.  51948e  and  51948f,  respectively. 

Ih.  Top  and  side  view  of  cast  of  the  interior  of  a  ventral  valve,  the  type  specimen,  from  Locality  41,  Lower 
Cambrian  decomposed  limestone,  from  Manuels  Brook,  Conception  Bay,  Newfoundland.  L^.  S.  Nat. 
Mus.  Cat.  No.  lS322a.  • 

li.  Cast  of  the  interior  of  a  dorsal  valve,  associated  with  specimen  represented  by  figure  Ih.  U.  S.  Nat.  Mus. 
Cat.  No.  18322b. 

Obolei.la  (Glyptias)  favosa  (Linnarsson)  (p.  600). 

Figure  2.  Exterior  and  side  view  of  ventral  valve.     U.  S.  Nat.  Mus.  Cat.  No.  3.52G4a. 
2a.  Exterior  and  side  view  of  dorsal  valve.     U.  S.  Nat.  Mus.  Cat.  No.  3.5264b. 

2b.  Cast  of  the  interior  of  ventral  valve  that  retains  a  portion  of  the  shell.     U.  S.  Nat.  Mus.  Cat.  No.  35264c. 
2c.  Cast  of  the  interior  of  small  dorsal  valve.     V.  S.  Nat.  Mus.  Cat.  No.  3.5264d. 
2d.  Outer  surface  of  shell  greatly  enlarged.     U.  S.  Nat.  Mus.  Cat.  No.  35264e. 

The  specimens  represented  b\-  figures  2.  2a-d  are  from  Locality  309c,  Lower  Cambrian  sandstone  at  Billingen, 
Province  of  Skaraborg,  Sweden. 

Obolella  mobergi  Walcott  (p.  597). 

Figures  3  and  3a.  Exterior  and  side  view  of  ventral  valve,  drawn  fmm  a  cast  taken  in  a  natural  mold  in  sandstone. 

Original  in  the  collection  of  the  Geological  Mu.sotini.  Lund,  Sweden;  cast  in  the  United  States  National 

Mu.seum  (Cat.  No,  352Gla). 
3b.  Posterior  view  of  specimen  represented  liy  figure  3,  showing  area  and  cast  of  pedicle  slit. 
3c.  Ca.st  in  fine  sandstone  of  interior  of  ventral  valve,  the  type  specimen.     U.  S.  Nat.  Mus.  Cat.  No.  35261b. 
3d.  Enlargement  of  a  natural  cast  of  a  portion  of  the  outer  surface.     U.  S.  Nat.  Mus.  Cat,  No.  3.5261c, 
3e.  Cast  of  the  interior  of  a  dorsal  valve.     U.  S.  Nat.  Mus.  Cat.  No.  35261d. 
3f.  Cast  of  the  interior  of  a  dorsal  valve.     V.  S.  Nat.  Mua.  Cat.  No.  35261e. 

The  specimens  represented  are  all  from  Localily  321s,  Lower  Cambrian  sandstone  at  Sularp,  near  Lund.  Province 
of  Malmohus,  Sweden. 
180 


U.  S.  GEOLOGICAL  SURVEY 


MONOGRAPH   LI     PL.   LV 


f«ANCC8  WIESES  ou. 


HEUOTVPE  CO..   BOSTON 


PLATE  LV.  181 

Obolella?  i.iNDSTROMi  Walcott  (p.  596). 

Figure  4.  Exterior  of  a  vciilral  valve,   the  type  specimen,   from   Locality  321v,    Lower  Cambrian   sandstone   at 
Bjorkelunda,  Province  of  Christianstad,  Sweden.     The  specimen  from  which  this  (i^iire  was  drawn 
can  not  be  located.     A  record  of  the  locality  wn.i,  however,  preserved. 
4a.  Cast  of  the  interior  of  dor.sal  valve,  from  Locality  321s,  Lower  Cambrian  sandstone  at  Sularp,  near  Lund, 
Province  of  Malmohus,  Sweden.     U.  S.  Nat.  Mu.s.  Cat.  No.  3.5263a. 

Obolella  crassa  elongata  Walcott  (p.  595). 

Figure  5.  Ventral  valve,  the  type  specimen  from  Locality  319b,  Lower  Cambrian  lime.stone  at  St.  Simon,  Quebec, 
Canada.     U.  S.  Nat.  Mus.  Cat.  No.  14691a. 
5a.  Dorsal  valve  a.ssociated  with  specimen  represented  by  figure  5.     U.  S.  Nat.  Mus.  Cat.  No.  14691b. 

Obolella  asiatica  Walcott  (p.  588). 

Figure  fi.  Exterior  of  ventral  valve,  the  type  specimen.    U.  S.  Nat.  Mus.  Cat.  No.  .52525a. 
6a.  Exterior  of  dor.sal  valve.     U.  S.  Nat.  Mus.  Cat.  No.  52.525b. 

The  specimens  represented  are  both  from   Locality  C32',  Lower  Camlirian  limestone  bnwlder  1  mile  south  of 
Chonpinghien,  on  Nankiang  River,  Shensi,  China. 

Obolella  wirrialpensis  Etlieridge  (p.  599). 

Figures  7  and  7'.  Top  and  side  views  of  ventral  valve.     University  of  Adelaide,  South  Australia. 

7a.  Exterior  of  dorsal  valve  marked  by  strong  concentric  ridges.     IT.  S.  Nat.  Mus.  Cat.  No.  51963a. 
7b.  Dorsal  valve.     Universitv  of  Adelaide,  South  Australia.     Type  specimen,  figured  by  Etheridge  [1905, 
PI.  XXV,  fig.  2]. 

The  specimens  represented  by  figures   7,   7a-b  are  all  from  Locality  315d,  Lower?  Cambrian  limestone  near 
Wirrialpa,  Flinders  Range,  South  Australia. 


PLATE    LVI. 


183 


PLATE  LVI. 

cl.  Cardinal  scars.  s.  Median  septum. 

F'.  Cast  of  toraminal  tube. '  v.  Visceral  area, 

fa.  False  area.  vs.  Vascular  sinuses, 

j.  Anterior  lateral  muscle  scar.  x'.  Cast  of  risceral  cavity. 

AcROTHELE  CORIACEA  Linnarssoii  (p.  642). 

Figure  1.  Top  and  back  view  of  ventral  valve  from  Locality  334f,  Middle  Cambrian  limestone  on  Bomholm  Island, 

Denmark.     U.  S.  Nat.  Mus.  Cat.  No.  .519S3a. 
la.  Interior  of  a  ventral  valve  from  Locality  320f,  Middle  Cambrian  limestone  at  Andrarum,  Province  of 

Christianstad,  Sweden.    U.  S.  Nat.  iltis.  Cat.  No.  1820Sa. 
lb.  Cast  of  interior  of  a  ventral  valve  associated  with  the  specimen  represented  by  figure  la.    V.  S.  Nat. 

Mus.  Cat.  No.  18208b. 
Ic.  Cast  of  interior  of  a  ventral  valve  associated  with  the  specimen  represented  by  figure  la.     U.  S.  Nat. 

Mus.  Cat.  No.  18208e. 
Id  and  le.  Interiors  of  dorsal  valves  associated  with  the  specinien  represented  by  figure  la.     U.  S.  Nat.  Mus. 

Cat.  Nos.  1S20SC  and  18208d,  respectively. 
If.  Cast  of  interior  of  a  dorsal  valve  associated  with  the  specimen  represented  by  figure  la.     U.  S.  Nat.  Mus. 

Cat.  No.  1820Sf. 
Is;.  Enlargement  of  the  surface  of  a  specimen  associated  with  the  shell  represented  by  figure  1.    U.  S.  Nat. 

Mus.  Cat.  No.  519S3b. 
Ih  and  Ih'.  Top  and  side  views  of  a  spiall  ventral  valve  from  Locality  8w,  Middle  Cambrian  limestones  at 

Andrarum,  Province  of  Christianstad,  Sweden,  showing  the  small  node  on  each  side  of  the  apex. 

U.  S.  Nat.  Mus.  Cat.  No.  5I97Sa. 
li.  Top  and  back  view  of  a  very  small  ventral  valve  associated  with  the  shell  represented  by  figure  Ih,  showing 

a  central  posterior  node,  and  a  small  noeje  on  each  side  of  the  apex.     V .  S.  Nat.  Mus.  Cat.  No.  51978b. 

AcROTHELE  (Redlichella)  graxvlata  (Linnarssoii)  (p.  663). 

Figure  2.  Top  and  side  views  of  exterior  of  a  ventral  valve  from  Locality  8z,  Middle  Cambrian  limestones  of  the 

Parado.ridts  celandiais  zone  at  Corgholm.  Oeland  Island,  Sweden.     V .  S.  Nat.  Mus.  Cat.  No.  51991a. 
2a.  Interior  of  a  ventral  valve  from  Locality  310o,  Middle  Cambrian  limestones  of  the  Paradoxides  tcssini  zone 

at  Borgholm,  Oeland  Island,  Sweden.    IT.  S.  Nat.  Mus.  Cat.  No.  56643a. 
2b.  Cast  of  the  interior  of  a  ventral  valve  from  Locality  309f,  Middle  Cambrian  shale  at  Borgholm,  Oeland 

Island,  Sweden.     U.  S.  Nat.  Mus.  Cat.  No.  23S97a. 
2c.  Interior  of  a  ventral  valve  associated  with  the  shell  represented  by  figure  2,  showing  visceral  area.     U.  S. 

Nat.  Mus.  Cat.  No.  51991b. 
2d.  Top  and  side  views  of  exterior  of  a  dorsal  valve  associated  with  the  shell  represented  by  figure  2.    V.  S. 

Nat.  Mus.  Cat.  No.  51991c. 
2e.  Interior  of  a  dorsal  valve  associated  with  the  shell  represented  by  figure  2.     T.  S.  Nat.  Mus.  Cat.  No. 

51991d. 
2f.  Exterior  of  a  dorsal  valve  associated  with  the  shell  represented  by  figure  2b,  showing  elongate  tubercles 

at  the  apex.     U.  S.  Nat.  Mus.  Cat.  No.  23S97b. 
2g.  Enlargement  of  the  surface  of  the  specimen  represented  by  figure  2f.    L'.  S.  Nat.  Mus.  Cat.  No.  23S97b. 
2h.  Exterior  of  a  dorsal  valve  from  Locality  320b,  Middle  Cambrian  limestones  at  Gudhem,  Pro\-ince  of 

Skaraborg,  Sweden.    U.  S.  Nat.  Mus.  Cat.  No.  51992a. 
2i.  Cast  of  an  interior  of  a  ventral  valve  associated  with  the  dorsal  valve  represented  by  figure  2h,  showing 

the  cast  of  the  visceral  area  (v),  the  expanded  interior  opening  of  the  foraminal  tube  (F'),  a'"'  niain 

vascular  sinuses  (vs).     U.  S.  Nat.  Mus.  Cat.  No.  .51992b. 
2],  Partly  exfoliated  ventral  valve  from  Locality  309f,  Middle  Cambrian  shale  at  Borgholm,  Oeland  Island, 

Sweden,  showing  the  main  vascular  sinuses  and  branches.     U.  S.  Nat.  Mus.  Cat.  No.  23897c. 
2k.  Fragment  of  the  interior  of  a  ventral  valve  associated  with  the  shells  represented  by  figures  2h  and  2i, 

greatly  enlarged  so  as  to  show  the  outline  of  the  visceral  area.     U.  S.  Nat.  Mus.  Cat.  No.  51992e. 
184 


U.  S.  GEOLOGICAL  SURVEY 


MONOGRAPH   LI     PL.  LVI 


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i:;a 


f2SEi??^SE?i»affiiSg3i31 


R  .i^, 


I 

M 


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li 


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FRANCES  WIES£R  DEL. 


HELIOTYPE  CO..  BOSTON. 


PLATE  LVI.  185 

AcROTHELE  (Redlichella)  GRANULArA  (Liiuiiirsson) — Continued. 

Figure  21.  fast  of  the  interior  of  a  dorsal  valve  associated  with  the  8))ecimen  represented  by  figure  2j.     U.  R.  Nat. 
Mus.  Cat.  No.  23897d. 
2m  and  2n.  Side  and  posterior  views  of  a  shell  in  whieh  the  two  valves  are  united,  as80ciate<l  with  the  shell 
represented  by  fi<;iire  2.     V.  S.  Nat.  Mus,  Cat.  No.  51991e. 

AcROTHELE  INTERMEDIA  Linnarsson  (p.  646). 

Figures  3  and  3a.  Ventral  valve,  the  type  specimen,  with  side  outline,  X-1.     Copied  from  l.innar.sson  [1879,  PI.  Ill, 

figs.  40  and  41]. 
3b.  Interior  of  a  ventral  valve,  showing  main  vascular  canals  and  branches,  X-i.     Copied  from  Linnarsson 

[1879,  PI.  Ill,  fig.  43]. 
3c.  Cast  of  the  interior  of  a  ventral  valve.     Copied  from  Linnarsson  [1879,  PI.  Ill,  fig.  42|. 
3d.  Cast  of  the  interior  of  a  broken  dorsal  valve.     Copied  from  Linnar.'sson  [1879,  PI.  Ill,  fig.  44]. 

The  specimens  represented  by  figures  3,  3a-c  are  from  Locality  320k,  Middle  Cambrian  limestones  of  the  Coro- 
nnlux  zone  at  Kiviks  Esperod,  Province  of  Malmohus;  the  specimen  represented  by  figure  3d  is  from  Locality  3201, 
the  same  horizon,  at  Andrarum,  Province  of  Christianstad;  both  in  Sweden.  ^ 


PLATE   LVII. 


187 


PLATE  LVII. 

cl.  Cardinal  scare.  «•  Median  septum. 

F.  Foramen.  v.  Visceral  area. 

F'.  Cast  of  pedicle  tube.  vs.  Vascular  sinus. 

AcROTHELE  BOHEMiCA   (Barraiule)   (p.  639). 

Figures  1  and  1'.  Top  and  side  views  of  ventral  valve,  the  type  specimen,  from  Locality  345c,  Middle  Cambrian 

shales  at  Mlestbitz,  Bohemia.     Copied  from  Barrande  [1879b,  PI.  CII,  figs,  vii:  lA  and  IB],  where 

they  are  labeled  Obolus  ?  hohcmims. 
la  and  la'.  Top  and  side  ^iews  of  a  dorsal  valve  associated  with  the  ventral  valve  represented  by  figure  1. 

Copied  from  Barrande  [1879b,  PI.  CII,  figs,  vii:  2A  and  2B],  where  they  are  labeled  OhoUts  1  hohimicus. 
lb.  Ventral  valve  from  Locality  345,  Middle  Cambrian  shales  on  the  DlouhA  Hora,  above  the  brook  of  Sbirov, 

near  Skrej,  Bohemia.     Copied  from  Pompeckj  [189(Jb,  PI.  XIV,  fig.  8b]. 
Ic.  Dorsal  valve  from  the  locality  represented  by  figure  lb.     Copied   from  Pompeckj  [1896b,  PI.  XIV, 

fig.  lib]. 
Id.  Interior  of  dorsal  valve  from  the  locality  represented  by  figure  lb.     Copied  from  Pompeckj  [1896b,  PI. 

XIV,  fig.  10b]. 

AcROTHELE  siACX.'LATA  (Salter)   (p.  647). 

[PI.  LVIII,  flg.2.] 

Figure  2.  Exterior  of  dor.sal  valve. 
2a.  Extericir  of  dorsal  valve. 
2b.  Cast  of  the  interior  of  a  dorsal  valve,  the  type  specimen. 

Figures  2,  2a-b  are  copied  from  Davidson  [1868,  PI.  XVI.  figs.  1-.3];  the  same  figures  being  copied  by  Davidson  in 
his  later  work  [1871,  PI.  L.  tig.s.  18. 19,  and  21].  Davidson  states  that  the  specimens  are  from  Porth-y-rhaw,  St.  Davids, 
and  from  Gwjaifvaiydd  and  Camlaii.  North  Wales. 

AcROTHELE  BELLAPUNCTATA  Wakott  (p.  636). 

Figure  3.  Exterior  of  partly   exfoliated  ventral  valve,  the  type  specimen.     U.  S.  Nat.  Mus.  Cat.  No.  51972a. 
Copied  from  Walcott  [1908d,  PI.  VIII,  fig.  9]. 
3a.  Exterior  of  partly  exfoliated  dorsal  valve.     U.  S.  Nat.  Mus.  Cat.  No.  51972b. 

3b.  Siu-face  of  outer  layer  enlarged  15  diameters.     V.  S.  Nat.  Mus.  Cat.  No.  51972c.     A  portion  of  the  surface 
*  represented  by  figure  3b  was  illustrated  by  Walcott  [1908d,  PI.  VIII,  fig.  9']  as  the  surface  of  the 

specimen  represented  by  figui-e  3;  it  is,  however,  taken  from  another  specimen. 
The  specimens  represented  are  all  from  Locality  8v,  Lower  Cambrian  shales  at  Eingsaker.  near  Lake  Mjosen, 
Province  of  Hedemarken,  Norway. 

BOTSFORDIA    GRANO.ATA    (RcclUcll)     (p.  605). 

Figure  4.  Cast  of  exterior  of  an  almost  perfect  specimen  of  the  transversely  oval  form  of  the  ventral  valve.     U.  S. 
Nat.  Mus.  Cat.  No.  52046s. 

4a.  Exterior  of  a  longitudinally  elongate  oval  form  of  the  ventral  vahe.     U.  S.  Nat.  ilus.  Cat.  No.  52046a. 

4b.  Exterior  of  a  transversely  oval  dorsal  valve,  preserving  the  two  small  .sharp  tubercles  at  the  apex.  U.  S. 
Nat.  Mus.  Cat.  No.  52046b. 

4c.  Posterior  portion  of  a  ventral  valve,  showing  the  pedicle  aperture.     U.  S.  Nat.  Mus.  Cat.  No.  5204Gc. 

4d.  Posterior  portion  of  a  ventral  valve,  showing  a  crescentiform  tubercle  on  each  side  of  and  a  small  tubercle 
just  back  of  the  depression  at  the  apex;  the  pedicle  aperture  is  just  back  of  the  posterior  tubercle 
and  in  fact  appears  to  come  up  through  it.     L'.  S.  Nat.  Mus.  Cat.  No.  52040d. 

4e.  Exterior  view  of  elongate  form  of  dorsal  valve.     V.  S.  Nat.  Mus.  Cat.  No.  52046e. 

4f  and  4f'.  Exterior  and  side  view  of  a  ventral  valve  intermediate  in  outline  between  the  specimens  repre- 
sented by  figures  4  and  4a.     U.  S.  Nat.  Mus.  Cat.  No.  52046f. 

4g.  Cast  of  interior  of  ventral  valve.     U.  S.  Nat.  Mus.  Cat.  No.  52046g. 
188 


U.  S.  GEOLOGICAL  SURVEY 


MONOGRAPH   LI     PL.   LVIl 


FRANCES  WIESER  DEL. 


HELIOTVPE  CO..  BOSTON 


PLATE  LVII.  189 

BoTSFORDiA  GRANULATA  (Redlicli) — Continued. 

Figure  4h.  Partly  exfoliated  ventral  valve,  showing  the  impression  of  the  main  vascular  sinuses  on  the  inner  layers 
of  the  shell.     U.  S.  Nat.  Mus.  Cat.  No.  52040h. 
4i.  Cast  of  interior  of  a  small  ventral  valve.     U.  S.  Nat.  Mus.  Cat.  No.  52046i. 
4j.  Cast  of  interior  of  a  dorsal  valve.     U.  S.  Nat.  Mus.  Cat.  No.  .52046J. 
4k.  Interior  of  a  small  dorsal  valve.     U.  S.  Nat.  Mus.  Cat.  No.  52046k. 
4  1.  Partly  exfoliated  dorsal  valve.     U.  S.  Nat.  Mus.  Cat.  No.  52046  1. 
4m.  Interior  of  a  dorsal  valve.     U.  S.  Nat.  Mus.  Cat.  No.  .52046m. 
4n  and  4o.  Exteriors  of  dorsal  valves,  showing  variation  in  outline,  as  compared  with  figure  4b,  and  in  small 

,  tubercles  near  the  apex.     U .  S.  Nat.  Mus.  Cat.  Nos.  52046n  and  52046o,  respectively. 
4p.  Interior  of  a  ventral  valve.     U.  S.  Nat.  Mus.  Cat.  No.  52046p. 
4q.  Exterior  of  one  of  the  largest  ventral  valves.     U.  S.  Nat.  Mus.  Cat.  No.  52046q. 
4r.  Enlargement  of  surface  to  show  granulations.     U.  S.  Nat.  Mus.  Cat.  No.  52040r. 

The  specimens  represented  are  all  from  Locality  15r,  Middle  Cambrian  shale  at  Khussak,  Salt  Range,  India. 

ACROTHELE    QtTADRILINEATA    Pompeckj     (p.  655). 

Figure  5.  Top  and  side  views  of  the  type  specimen,  a  ventral  val\-e,  from  Locality  345d,  Middle  Cambrian  shales 
at  Skrej,  Bohemia.     Copied  from  Pompeckj  [1896b,  PI.  XIV,  figs.  6b  and  6c]. 

AcROTHELE  PRiMiEVA   (de  Verncuil  and  Barrande)    (p.  654). 

Figures  6  and  0'.  Top  and  side  views  of  the  type  specimen,  a  ventral  valve,  from  Locality  350,  Middle  Cambrian 
limestone  near  .Vdrados,  Cantabrian  Mountains,  Pro^^nce  of  Leon,  Spain.  Cojjied  from  de  Verneuil 
and  Barrande's  figures  [1860,  PL  VIII,  figs,  2  and  2a]  of  Discina  (Orhict'Un  primxva. 

BoTSFORDIA?    BARRANDEI    Walcott    (p.   602). 

Figure  T.  Dorsal  view  of  the  type  specimen,  showing  apex  of  ventral  valve,  from  Locality  350,  Middle  Camljrian 
limestone  near  Adrados,  Cantabrian  Mountains,  Province  of  Leon,  Spain. 
7a  and  7b.  Posterior  and  side  views  of  the  specimen  represented  by  figure  7. 

Figures  7,  7a-b  are  copied  from  de  Verneuil  and  Barrande's  figures  [1860,  PI.  VIII,  figs.  5,  5a-b]  of  "  Brachiopode, 
nouv.  gen." 


PLATE   LVIII. 


191 


PLATE  LVIII. 

cl.  Cardinal  soars.  h.  Central  muscle  scar. 

F.  Foramen.  s.  Median  septum. 

F'.  Cast  of  foraniiiKil  tube.  v.  Visceral  area, 

fa.  False  area.  vs.  Vascular  sinuses. 

ACROTHKLE    PRETIOSA    (Billings)     ()).   ()r)2) . 

Figures  1  and  la.  Exteriors  of  crushed  and  sliyluly  dis^toricil  \cniral  valves.    L'.  S.  Nat.  Mus.  Cat.  Nos.  52004a  and 

52004b,  respectively. 
lb.  Partly  exfoliated  and  compressed  ventral  valve.    I'.  S.  Na(.  Miis.  Cat.  No.  52004c. 
Ic.  Exterior  of  a  dorsal  valve.    U.  S.  Nat.  Mus.  Cat.  No.  52004d. 
Id.  Cast  of  the  interior  of  a  dorsal  valve.     U.  S.  Nat.  Mus.  Cat.  No.  52004e. 
le.  Interior  of  dorsal  valve.     V.  S.  Nat.  Mus.  Cat.  No.  52004f. 
If.  Cast  of  interior  of  a  dorsal  valve,  showing  median  septum  e.xlending  well  toward  Ihe  front  margin.     U.  S. 

Nat.  Mus.  Cat.  No.  .52004g. 
Ig.  Interior  of  dorsal  valve.     U.  S.  Nat.  Mus.  Cat.  No.  .')2004h. 

The  specimens  represented  are  all  from  Locality  220a,  ( )rdovi<-ian  shales  at  the  Grand  Trunk  railroad  bridge  over 
Chaudiere  River,  Quebec,  Canada. 

ACROTHELE    MACUL.\TA    (.Saltei-)     (p.  647). 
(PI.  LVII,  figs.  2,  2a-b.] 

Figure  2.  Exterior  of  distorted  and  com])ressed  ventral  valve  from  Locality  3181i,  Middle  Cambrian  Menevian  shales 
of  St.  Davids,  South  Wales.     U.  S.  Nat.  Mus.  Cat.  No.  51993a. 

AcROTHELE  DECiPiEXs  Walcott   (p.  644). 

Figure  3.  Exterior  of  ventral  valve  with  side  and  transverse  outline.    L'.  S.  Nat.  Mus.  Cat.  No.  ^6435b. 

3a.  Partly  exfoliated  ventral  valve,  the  type  specimen,  with  the  rim  of  the  foraminal  aperture  broken  off. 

U.  S.  Nat.  Mus.  Cat.  No.  26435a.     Specimen  figured  by  Walcott  [lS97b.  PI.  LX,  fig.  2], 
3b.  Exterior  of  dorsal  valve.     U.  S.  Nat.  Mus.  Cat.  No.  2()43oc. 
3c.  Interior  of  a  compressed  dofsal  valve.     U.  S.  Nat.  Mus.  Cat.  No.  26435d. 
3d.  Cast  of  an  interior  of  a  distorted  dorsal  valve.     IT.  S.  Nat.  Mus.  Cat.  No.  26435e. 

The  specimens  represented  are  all  from  Locality  50,  Lower  Cambrian  .shale,  1.125  miles  north  of  Stoner,  York 
County,  Pennsylvania. 

ACROTHELE    NITIDA    (Fdl'll)     (p.  650). 

Figure  4.  Exterior  of  the  type  specimen,  a  dorsal  vahe,  from  Locality  27,  Lower  Cambrian  limestone  in  the  eastern 
suburb  of  Troy,  New  York.     U.  S.  Nat.  Mus.  Cat.  No.  15353a.     Specimen  figured  jWaU-ott,  1886b, 
PI.  XI,  fig.  2]  as  Obolella  nitida. 
4a.  Interior  of  dorsal  valve  associated  with  the  specimen  represented  by  figure  4.     U.  S.  Nat.  Mus.  Cat.  No. 
15353b. 

ACROTIIELE    BELLULA    Walcott     (p.  637). 

Figure  5.  Exterior  of  a  small  ventral  valve,  the  typo  specimen,  from  Locality  90x,  Middle  Cambrian  siliceous  nodules 
in  Coosa  Valley,  Cherokee  County,  Alabama.  U.  S.  Nat.  Mus.  Cat.  No.  26436a.  Another  specimen 
(Cat.  No.  26436b)  was  used  in  restoring  certain  portions  of  this  figure.  Copied  from  Walcott  [1897b, 
PI.  LX,  fig.  4]. 

5a.  Cast  of  the  interior  of  a  slightly  distorted  ventral  valve  from  Locality  94x,  Middle  Cambrian  shale  near 
Givens  Mill,  Cowan  Creek,  Cherokee  County,  Alabama.  A  porti(m  of  the  shell  is  jireserved  near 
the  apex.    U.  S.  Nat.  Mus.  Cat.  No.  56602a."    Copied  from  Walcott  [1897b,  PI.  LX,  fig.  4a]. 

5b.  Natural  cast  of  the  foraminal  tube  of  a  specimen  associated  with  the  shell  represented  by  figure  5. 
V.  S.  Nat.  Mus.  Cat.  No.  26436c. 
192 


U.  S.   GEOLOGICAL  SURVEY 


MONOGRAPH   LI     PL.  LVIII 


&lm 


FRANCES  WieSER  DEL. 


HELIOTYPE  CO..  BOSTON. 


PLATE  LVIIl.  193 

AcROTHELE  BELLULA  Walcott — Continued. 

Figure  5c.  Enlargement  of  the  cast  of  the  interior  of  a  ventral  valve  associated  with  the  shell  represented  by  figure  5. 

IT.  S.  Nat.  Mus.  Cat.  No.  2fi43fid.     Copied  from  Walcott  [1897b,  PI.  LX,  fig.  4b].     In  thi.s  figure  the 

line  indicating  the  cardinal  scar  is  extended  a  little  too  far.     It  should  have  stopped  before  reaching 

the  depression. 
5d.  Cast  of  the  posterior  ])ortiou  of  the  interior  of  a  ventral  valve  associated  with  the  shell  represented  by 

figure  5.     U.  S.  Nat.  Mus.  Cat.  No.  26436e.     In  this  figure  the  line  indicating  the  cardinal  scar  is 

extended  a  little  too  far.     It  should  have  stopped  before  reaching  the  depression. 
5e.  Cast  of  the  interior  of  a  small  ventral  valve  associated  with  the  shell  represented  by  figure  5,  showing 

vascular  sinuses.     U.  S.  Nat.  Mus.  Cat.  No.  26436f. 
5f .  Interior  of  a  dorsal  valve  drawn  from  a  cast  of  the  specimen  represented  by  figure  5g,  showing  the  area, 

median  septum,  and  diverging  vascular  sinuses.     U.  S.  Nat.  Mus.  Cat.  No,  26436g.     Another  specimen 

(Cat.  No.  26436h)  was  used  in  restoring  certain  portions  of  this  figure  and  of  figure  5g.     Copied  from 

Walcott  [lS97b,  PI.  LX,  fig.  4c]. 
5g.  Natural  cast  of  the  interior  of  a  dorsal  valve  from  Locality  90x,  Middle  Cambrian  siliceous  nodules,  Coosa 

Valley,  Cherokee  County,  Alabama.     A  cast  of  this  specimen  is  represented  by  figure  of.    U.  S.  Nat. 

Mus.  Cat.  No.  26436g.     Copied  from  Walcott  [1897b,  PI.  LX,  fig.  4d]. 
5h.  Cast  in  shale  of  the  interior  of  a  dorsal  valve  from  Locality  94x,  Middle  Cambrian  shales  near  Givens  Mill, 

Cowan  Creek,  Cherokee  County,  Alabama.    The  cardinal  muscle  scar  is  drawn  too  far  away  from 

the  median  line.     It  should  be  about  the  length  of  the  scar  from  the  median  line.     V.  S.  Nat.  Mub. 

(Cat.  No.  .56fi02b.     Cojuod  from  Walcott  [1897b,  PI.  LX,  fig.  4e]. 

AcROTHELE    BERGERONI    Walcott    (p.  63S). 

Figures  6  and  6a.  Exteriors  of  compressed  and  slightly  distorted  ventral  valves.     U.  S.  Nat.  Mus.  Cat.  Nog.  51975b 
and  51975c,  respectively. 
6b.  Cast  of  the  interior  of  a  compressed  and  distorted  ventral  valve.     U.  S.  Nat.  Mus.  Cat.  No.  51975d. 
6c.  Cast  of  the  interior  of  a  dorsal  valve,  the  type  specimen,  flattened  in  the  shale.    U.  S.  Nat.  Mus.  Cat. 
No.  51975a.     Copied  from  ^Valcott  [1908d,  PI.  VIII,  fig.  11]. 

The  specimens  represented  are  all  from  Locality  342,  Middle  Cambrian  shales  in  Montague  Noire,  Coulouma, 
H6rault,  France. 
62667°— VOL  51,  pt  2—12 13 


PLATE   LIX. 


195 


PLATE  LIX. 

a.  Area.  s.  Median  septum. 

cI.  Cardinal  scars.  v.  \'isci>ral  area. 

F'.  Cast  of  foraminal  tube.  vs.  Vascular  sinus. 

BOTSFORDI.V    C.ELATA   (Hall)    (p.  60.3). 
[H.  LIX,  figs.  3,  3a-b.] 

FiociiE  1.  Partly  exfoliated,  broken  ventral  valve  from  Locality  2o,  Lower  Cambrian  limestone  bowlders  at  entrance 

to  Kic  Harbor,  Quebec,  Canada.     U.  S.  Nat.  Mus.  Cat.  No.  3.5L'.59a. 
la.  Fragment  of  a  large  ventral  valve  from  Locality  2b,  Lower  Cambrian  limestone  nnrlh  ni  IScman  Park,  near 

Troy,  New  York.     U.  S.  Nat.  Mus.  Cat.  No.  52040a. 
lb.  Top,  side,  and  back  views  of  a  ventral  valve  associated  with  Ihe  shell  represented  by  figure  la,  showing 

the  foraminal  aperture.     U.  S.  Nat.  Mus.  Cat.  No.  52040b. 
Ic.  Broad  form  of  ventral  valve  from  Locality  27,  Lower  Cambrian  limestone  in  the  eastern  suburb  of  Tn>y, 

New  York.     U.  S.  Nat.  Mus.  Cat.  No.  15325a.     Specimen  figured  [Walcott,  1886b,  I'l.  VII,  (ig.  IbJ  as 

LinguhUa  cxlata. 
Id.  Small  ventral  valve  associated  with  the  shell  represented  by  figure  1.     U.  S.  Nat.  Mus.  Cat.  No.  35259b. 
le.  Cast  of  part  of  the  interior  of  a  ventral  valve  from  Locality  2p,  Lower  Cambrian  limestone  a  little  west  of 

Bic,  Quebec,  Canada.     U.  S.  Nat.  Mus.  Cat.  No.  56874a. 
If.  Interior  of  a  small  ventral  valve  from  Locality  36a,  Lower  Cambrian  limestone  on  Bald  Mountain,  Washing- 
ton County,  New  York.     U.  S.  Nat.  Mus.  Cat.  No.  52037a. 
Ig.  Fragment  of  the  interior  of  a  ventral  valve  from  Locality  29a,  Lower  Cambrian  limestone  at  Schodack, 

Rensselaer  County,  New  York.     V.  S.  Nat.  Mus.  Cat.  No.  "l.5323a. 
Ih.  Enlargement  of  a  portion  of  the  exterior  siu-face  of  a  ventral  \alve  associated  with  the  specimen  represented 

by  figure  1.     U.  S.  Nat.  Mus.  Cat.  No.  35259c. 
li.  Partly  exfoliated  dorsal  valve  associated  with  the  specimen  represented  by  figure  la.     U.  S.  Nat.  Mus. 

Cat.  No.  52040c. 
Ij.  Posterior  portion  of  a  dorsal  valve  associated  with  the  specimen  represented  by  figure  la.     U.  S.  Nat.  Mus. 

Cat.  No.  52040d. 
Ik.  Cast  of  the  posterior  portion  of  the  interior  of  a  dorsal  \alve  associated  with  specimen  represented  by  figure 

la.     U.  S.  Nat.  Mus.  Cat.  No.  52040e. 

II.  Partly  exfoliated  dorsal  valve  from  Locality  35,  Lower  Cambrian  limestone  1.5  miles  north  of  Bald  Moun- 

tain, Washington  County,  New  York.     V.  S.  Nat.  Mus.  Cat.  No.  17457a. 
Im.  Partly  exfoliated  dorsal  valve  associated  with  the  specimen  represented  by  figure  la,  showing  cast  of  llr,' 

median  septum  and  main  vascular  sinuses.    U.  S.  Nat.  Mus.  Cat.  No.  52040f. 
In.  Fragment  of  a  cast  of  the  interior  of  a  dorsal  valve.    The  true  outline  of  this  specimen  and  the  locality  arc 

unknown.     Am.  Mus.  Nat.  Hist.,  New  York. 

III.  Enlargement  of  surface  of  a  dorsal  valve  associated  with  the  specimen  represented  by  figure  Ic.     U.  S. 

Nat.  Mus.  Cat.  No.  15325b.     Specimen  figured  [Walcott,  188Gb,  PI.  VII,  fig.  Id]  as  Llngiilrlla  cselata. 
Ip  and  Ip'.  Thin  section  of  limestone  containing  many  shells  of  the  species  from  Locality  2b,  Lower  Cambrian 

limestone  north  of  Beman  Park,  Troy,  New  York.     V.  S.  Nat.  Mus.  Cat.  No.  52040g. 
Iq.  Exfoliated  ventral  valve  showing  cast  of  pedicle  opening  and  visceral  ca\-ity,  from  Locality  29a,  Lower 

Cambrian  limestone  at  Schodack,  Rensselaer  County,  New  York.     L'.  S.  Nat.  Mus.  Cat.  No.  15323b. 

MicKWiTziA  MONiLiFERA  (Linnarssoii)  (p.  3.30). 

[I'l.  \l.  rigs.  1,  la-p.) 

Figure  2.  Top  and  side  views  of  the  posterior  portion  of  a  ventral  valve  from  Locality  396v,  Lower  Cambrian  sandstone 
below  the  cement  factory  on  Kunda  Bmok,  (iiivernmciU  of  Esthonia,  Russia.  U.  S.  Nat.  Mus.  Cat. 
No.  61522a. 

BOTSFOKDIA    C'.KI.ATA    (Hall)    (]).  603). 
|1'1.  LI.K.figs.  1,  la-q.l 

Figure  3  and  3a.  Top  and  back  views  of  a  ventral  valve  from  Locality  39a,  Lower  Cambrian  limestone  north  of  Easton 
Station,  Washington  County,  New  York.     I'.  S.  Nat.  Mus.  Cat.  No.  52039a. 
3b.  Interior  of  a  dorsal  valve  from  Locality  38,  Lower  Cambrian  limestone  3  miles  west  of  South  Granville, 
Washington  County,  New  York.     U.  S.  Nat.  Mus.  Cat.  No.  5203Sa. 
196 


U.  S.   GEOLOGICAL  SURVEY 


MONOGRAPH  LI     PL.  UX 


.s^;?'^:^ 


■1' 


PE  CO  aosroN 


PLATE  LIX.  197 

ACROTHELE   YORKENSIS  Walcott  (p.  661). 

Figure  4.  Extcrinr  of  tho  type  specimen,  a  distorted,  broken  ventral  valve,  from  Locality  48d,  Middle  Cambrian  shales 
iu  railroad   cut  at  York,  Pennsylvania.     U.  S.  Nat.  Mils.  Cat.  No.  520.31a.     Copied   from  Walcott 
[190Sd,  PI.  IX,  fig.  10]. 
4a  and  4b.  Compressed,  exfoliated  donsal  valves  associated  with  the  .specimen  represented  by  figure  4.     U.  S. 
Nat.  Mus.  Cat.  Nos.  520:Ub  and  .52031c,  respectively. 

AcROTHELE    PANDERI  Walcott   (p.  651). 

FiGUnE.s  5  and  5'.  Exterior  and  side  views  of  a  ventral  valve,  the  type  specimen,  from  Locality  4v,  Lower  Cambrian 

shales  on  Gordon  Creek,  Ovando  quadrangle,  Montana.     U.  S.  Nat.  Mus.  Cat.  No.  52003a. 
5a.  E.xterior  of  ventral  valve  as.sociated  with  the  shell  represented  by  figure  4.     U.  S.  Nat.  Mus.  Cat.  No. 

52003b. 
5b.  Exterior  of  ventral  valve  from  Locality  6j,  Lower  Cambrian  shales  6  miles  west-northwest  of  Scapegoat 

Mountain,  Coopers  Lake  cjuadrangle,  Montana.     V.  S.  Nat.  Mus.  Cat.  No.  52002a. 
5c.  Partly  exfoliated  dorsal  valve  associated  with  the  shell  represented  by  figure  5b.     U.  S.  Nat.  Mus.  Cat. 

No.  52002b. 


PLATE    LX. 


199 


PLATE  LX. 

cl.  Cardinal  sear.  ].  Anterior  ialeral  muscle  scar. 

fa.  Faise  area.  s.  Median  septum. 

h.  Centrai  muscle  scar.  vs.  Vascular  sinus. 

A.CKOTHELE  suBsiDUA  (White)  (p.  656). 

[PI.  LX,  fig.  8.) 

Figure  1.  Interior  of  a  ventral  valve  from  Locality  4  (?),  drift  pieces  believed  to  be  from  the  'WTieeler  formation, 

near  Antelope  Springs,  House  Range,  Utah,  showing  outline  of  false  area.     U.  S.  Nat.  Mus.  Cat.  Xo. 

15435a.     Type  specimen,  figured  by  ^Vhite  [1877,  PI.  I,  fig.  3a]  as  Acrotreta  f  subsidua. 
la.  Exterior  of  ventral  valve  from  Locality  163.  Middle  Cambrian  Spence  shale  member  of  Ute  limestone, 

Spence  Gulch,  15  miles  west  of  Montpelier,  Idaho.     U.  S.  Nat.  Mus.  Cat.  \o.  5201.5a. 
lb.  Exterior  of  an  exfoliated  ventral  valve  associated  with  the  specimen  represented  by  figure  la,  showing 

several  radiating  ribs.     U.  S.  Nat.  Mus.  Cat.  No.  52015b. 
Ic.  Exterior  of  a  small  ventral  valve  associated  with  tlie  specimen  represented  by  figure  la.     U.  S.  Nat.  Mus. 

Cat.  No.  52015c. 
Id.  Almost  perfect  ventral  valve  in  the  Langston  limestone.  Locality  5b,  2  miles  southeast  of  Malade,  Idaho. 

U.  S.  Nat.  Mus.  Cat.  No.  52014a. 
le.  A  cast  of  the  interior  of  a  ventral  valve  associated  with  llie  specimen  represented  by  figure  Id.    U.  S.  Nat. 

Mus.  Cat.  No.  52014b. 
If.  Cast  of  the  interior  of  a  ventral  valve  associated  with  the  specimen  represented  by  figure  1.     U.  S.  Nat. 

Mus.  Cat.  No.  52018a. 
Ig.  Exterior  of  a  dorsal  valve  associated  with  the  specimen  represented  by  figure  Id.     U.  S.  Nat.  Mus.  Cat. 

No.  .52014c. 
Ih,  li,  and  Ij.  Exteriors  of  dorsal  valves  associated  with  the  ventral  valve  represented  by  figure  la.     U.  S. 

Nat.  Mus.  Cat.  Nos.  52015d,  52015e,  and  .5201.5f,  respectively. 
Ik.  Interior  of  a  dorsal  valve  associated  with  the  specimen  represented  by  figiu-e  1.     U.  S.  Nat.  Mus.  (.'at. 

No.  15436a. 
1 1.  Interior  of  a  dorsal  valve,  showing  visceral  area,  and  muscle  scars  on  the  side  of  the  median  ridge.     Associ- 
"  ated  with  the  specimen  represented  by  figure  1.     U.  S.  Nat.  Mus.  Cat.  No.  52018b. 

Im.  Cast  of  interior  of  a  dorsal  valve  associated  with  the  specimen  represented  by  figiu-e  la.     U.  S.  Nat. 

Mus.  Cat.  No.  52015g. 
In.  Cast  of  interior  of  a  dorsal  valve  associated  with  the  specimen  represented  by  figure  1.     U.  S.  Nat.  Mus. 

Cat.  No.  15435b.     Specimen  figured  by  \\'hite  [1877,  PL  I,  fig.  3d]  as  ^icrotreta  ?  subsidua. 
lo.  Enlargement  of  the  apex  of  a  ventral  valve  7  mm.  in  length  on  which  the  tubercles  are  small  and  the 

pedicle  aperture  large.     Locality  30g,  Middle  Cambrian  Marjum  limestone  in  ridge  east  of  ^Mieeler 

Amphitheater,  House  Range,  Utah.     U.  S.  Nat.  Mus.  Cat.  No.  52016a. 

ACROTHELE    DICHOTOMA  Walcott   (p.  644). 

Figure  2.  Exfoliated  ventral  valve  from  Locality  58,  Middle  Cambrian  Secret  Canyon  shale  in  either  New  York  or 
Secret  Canyon,  Eureka  district,  Nevada,  showing  false  area,  main  vascular  sinuses,  and  apical 
callosity.  U.S.  Nat.  Mus.  Cat.  No.  24595a.  Type  specimen,  figured  by  Walcott  [1884b,  PL  IX, 
fi.g.  11]. 

ACROTHELE    SPURRI   Walcott  (p.   65fi). 

Figure  3.  Top  view  of  the  type  specimen,  which  is  a  partly  exfoliated  \enlral  valve,  from  Locality  31a,  Lower 
Cambrian  limestone  near  Pioche,  Nevada.  U.  S.  Nat.  Mus.  Cat.  No.  15344a.  Copied  from  Walcott 
[lOOSd,  PL  VIII,  fig.  14].  That  figure  was  redrawn  from  the  specimen  illustrated  by  Walcott  [lS8fib, 
PI.  IX,  fig.  4]  as  Acrothele  subsidua. 

3a  and  3b.  Back  and  side  views  of  a  partly  exfoliated  ventral  valve  a.ssociated  with  the  specimen  represented 
by  figure  3.  U.  S.  Nat.  .Mus.  Cat.  No.  1.5344b.  Copied  from  Walcott  [l!l08d,  PL  VIII,  figs.  14" 
and  14']. 

3c.  Exterior  of  an  exfoliated  dorsal  valve  associated  with  the  specimen  represented  by  figure  3.     U.  S.  Nat. 
-Mus.  Cat.  No.  15344c. 
200 


U.  S.   GEOLOGICAL  SURVEY 


MONOGRAPH   LI     PL.  LX 


r 


#: 


3' 


r 


r 


k 


9 


\ 


PRANCES  VUIESER  DEL. 


MCLlOTYPC    CO   BOSTOW 


PLATE  LX.  201 

ACROTHELE    GAMAGEI    (Hobbs)    (p.   (>45). 

Figures  5  and  5'.  Top  view  and  side  outline  of  a  ventral  valve.     U.  S.  Nat.  iMiis.  Cat.  .\o.  51986a. 
5a.  Cast  of  the  interior  of  a  ventral  valve.     U.  S.  Nat.  Mus.  Cat.  No.  51986b. 
5b  and  5b'.  Partly  exfoliated  specimen  of  a  dorsal  valve  and  side  outline  of  same.     Original  in  the  Museum 

of  Comparative  Zoology;  cast  in  the  United  States  National  Mu.seum  (Cat.  No.  51987a). 
oc.  Cast  of  the  interior  of  a  dorsal  valve.     U.  S.  Nat.  Mus.  Cat.  Xo.  51986c. 

The  specimens  represented  are  all  from  Locality  5,  Middle  Cambrian  siliceous  .shale  on  ilayward  Creek,  Braintree, 
Massachusetts.  * 

AcROTHELE    WOODWORTHI  Walcott   (|).   Gfil  ). 

Figure  U.  Top,  back,  and  side  views  of  a  cast  made  from  the  outer  siu-face  of  a  natural  mold  from  Localitv  326c, 
Lower  Cambrian  limestone  at  Nahant,  Essex  County,  Massachusetts.  Type  specimen  in  the  col- 
lection of  the  Boston  Society  of  Natiu-al  History;  cast  in  the  United  States  National  Museum  (Cat. 
No.  52030a).     Copied  from  Walcott  [1908d,  PI.  IX,  fig.  ll]. 

AcROTHELE    TURNERI    Walcott.   (p.  660). 

Figures  7  and  7'.  Top  and  side  views  of  a  partly  crushed  veutral  valvi-,  the  type  specimen,  from  Locality  7r,  Middle 
Cambrian  shales  4  miles  south-southeast  of  Emigi-ant  Peak,  Esmeralda  County,  Nevada.     U.  S.  Nat. 
Mus.  Cat.  No.  .52028a.     Copied  fi-om  Walcott  [1908d,  PI.  IX,  figs.  12  and  12']." 
7a.  Exterior  of  a  compres.sed  dorsal  valve  associated  with  the  specimen  represented  by  figure  7.     U.  S.  Nat. 
Mus.  Cat.  No.  52028b. 

AcROTHELE    .SUBSIDUA    OVllite)    (p.   6.o6). 

[PI.  LX,  flgs.  ],  la-o.l 

Figure  8.  Large  compressed  ^■entral  valve  from  Locality  14s,  Middle  ("ambrian  Ogi/gopsis  zone  on  Mount  Stephen, 
British  Columbia.     U.  S.  Nat.  Mus.  Cat.  No.  24063a. 

AcROTHELE    SUBSIDUA    HERA  Walcott  (p.  6.5i)). 

Figures  9  and  9'.  Top  and  side  views  of  an  exfoliated  ventral  valve,  the  type  .specimen,  showing  the  concentric 
striiB  and  radiating  ridges  on  the  inner  layers  of  the  shell.  From  Locality  31a,  Lower  Cambrian 
limestone  near  Pioche,  Nevada.  U.  S.  Nat.  Mus.  Cat.  No.  52024a.  Copied  from  Walcott  [1908d,  PL 
VIII,  figs.  15  and  15']. 


PLATE    LXI. 


203 


PLATE  LXI. 

cl.  Cardinal  scars.  s.  Median  sopttim. 

F'.  Oast  of  foraminal  tube.  vs.  Vascular  sinuses, 

ta.  False  area. 

ACROTHELE    MATTIIEWI    (Ilartt)    (p.  (547). 

Figure  1.  Ventral  valve  fi'om  Locality  301j,  Middle  Cainbriau,  St.  John  formation  at  Ratcliffs  Millstream,  St.  John 
County,  New  Brunswick.  Specimen  fip:ured  tiy  Walcolt  [1884a,  PI.  I,  ficr.  4a],  who  stales  that  it 
was  labeled  by  Hartt  as  No.  342,  Obolus  {Disciiin)  nitulus,  nov.  sp. 

la.  Dorsal  valve  from  Locality  301k,  Middle  Cambrian,  St.  John  formation  at  St.  John,  New  Brunswick. 
Type  specimen,  figured  by  Hartt  [18G8,  fig.  221,  p.  644],  and  by  Walcott  [1884a,  PI.  T,  fig.  4]. 

lb.  Top  and  side  views  of  an  interior  cast  of  a  ventral  valve  from  I^ocality  3,  Vpper  Cambrian  limestones  on 
Manuels  Brook,  Conception  Bay,  Newfoundland.     L'.  S.  Nat.  Mus.  Cat.  No.  .51004a. 

Ic.  Cast  of  the  interior  of  a  compressed  ventral  \alve  associated  with  the  shell  represented  by  figure  lb,  show- 
ing vascular  canals.     U.  S.  Nat.  Mus.  Cat.  No.  51004b. 

1<1.  Interior  of  a  ventral  valve  from  Locality  6n,  Mid<lle  Camlirian  shales  on  Manuels  Brook,  Conception  Bay, 
Newfoundland.     U.  S.  Nat.  Mus.  Cat.  No.  5109Ga. 

le.  Exterior  of  a  ventral  valve  from  Locality  6g,  Middle  Cambrian  limestone  at  Chappie  Arm  Harbor,  Trinity 
Bay,  Newfoundland.     U.  S.  Nat.  Mus.  Cat.  No.  51995a. 

If.  Interior  of  a  dorsal  valve  associated  with  the  shell  represented  by  figtire  Id.  T'.  R.  Nat.  Miis.  Cat.  No. 
51906b. 

Ig.  Interior  of  a  dorsal  valve  from  Locality  301j,  Middle  Cambrian  shales  on  Ratcliffs  Millstream,  St.  John 
County,  New  Bruns-iWck.     U.  S.  Nat.  Mus.  Cat.  No.  18170a. 

AcROTHELE    MATTHEW!    ERYX    Walcott   (p.  049). 

FiouRE  2.  Top  and  side  views  of  a  partly  exfoliated  \entral  valve,  the  type  specimen,  from  Locality  C4,  Middle 
Cambrian  limestone,  Kiulung  group,  3  miles  southwest  of  Yenchuaiig,  Sinlai  district,  .Shantung, 
China.     U.  S.  Nat.  Mus.  Cat.  No.  52520a. 

ACROTHELE    MATTHEWI    LATA    MattlieW   (]).  049). 

Figure  3.  Interior  of  a  crushed  dorsal  valve  from  Locality  301a,  Middle  Cambrian  sandstones  of  Division  lb3  on  Han- 
ford  Brook,  St.  John  County,  New  Brunswick.  University  of  Toronto,  Canada.  Type  specimen, 
figured  by  Matthew  [1886,  PI.  V,  figs.  17  and  17a]  and  by  Hall  and  Clarke  [1892c,  PI.  Ill,  figs.  26-28]. 

AcROTHELE    PRIMA    CO.STATA    (^[a(thow)    C]).  0.5.'^). 

Figure  4.  Top  view  of  a  broken  ventral  valve  with  numerous  co.stie,  from  Locality  21i,  Middle  Cambrian  sandstones 

of  Division  lb2  on  Hanford  Brook,  St.  John  County,  New  Brunswick.     L".  S.  Nat.  Mus.  Cat.  No. 

.5201  Oa. 
4a.  A  crushed  ventral  valve  with  three  costa"",  associated  with  the  shell  rciirescnlcd  by  figvire  4.     1'.  S.Nat. 

Mus.  Cat.  No.  52010b. 
4b.  Interior  of  a  broken  dorsal  valve  associated  with  tli<'  shell  represented  liy  figure  4.     1'.  S.  Nat.  Mus.  Cat. 

No.  .52010c. 
4c.  Interior  of  a  dorsal  valve  from  Locality  6n.  Middle  Cambrian  shales  on  Manuels  Brook,  Conception  Bay, 

Newfoundland.     U.  S.  Nat.  Mus.  Cat.  No.  51084a. 
4d.  Enlargement  of  the  outer  surface  of  a  specimen  associated  with  ihe  shell  rc])resented  by  figure  4.    U.  S. 

Nat.  Mus.  Cat.  No.  52010d. 
204 


U.   S.   GEOLOGICAL  SURVEY 


MONOGRAPH   LI     PL.  LXI 


/■        ( 


f-i^-- 


'- 1 


FRANCES  WIE9ER  DEL. 


HCLiOTypc  CO  eo5To« 


PLATE  LXI.  205 

ACROTHELE    MATTHEWI    MULTICOSTATA    MattheW   (p.  650). 

Figure  5.  Top  and  side  views  of  a  voiilral  valve  ]ii-eserving  the  outer  surface  from  Locality  21,  -Middle  Cambrian  shale 
at  the  base  of  the  Paradoxides  zone  on  llanford  Brook,  St.  John  County,  Xew  Brunswick.     V.  S.  Nat. 
Mus.  Cat.  No.  56633a. 
5a.  Partly  exfoliated  ventral  valve,  with  apex  broken  off.     Locality  2t,  Middle  t'ambrian  shales  at  Hastings 

Cove  on  Kennebecasis  Bay,  St.  John  County,  New  Brunswick.     U.  S.  Nat.  Mus.  Cat.  No.  .52000a. 
5b.  Fragment  showing  the  numerous  cost*.    University  of  Toronto,  Canada.     (Locality  unknown.) 
5c.  Exfoliated  dorsal  valve  associated  with  the  specimen  represented  by  figure  5a.     U.  S.  Nat.  Mus.  Cat.  No. 
52000b. 

AcROTiiELE  PRIMA  (Matthew)  (p.  ().53). 

[I'l.  LXII,  flg.  2.] 

Figure  6.  Top  view  of  a  small  ventral  \-alve  from  Locality  2g,  Middle  Cambrian  sandstones  of  Division  Ibl  of 
Matthew's  ProtoUnus  zone,  Hanford  Brook,  St.  John  County,  New  Brunswick.  University  of 
Toronto,  Canada.  Type  specimen,  figured  by  Matthew  [1886,  PI.  V,  figs.  16  and  16a]  as  Acrothele 
maUhevi  prima.    The  specimen  has  been  figured  and  refigured;  see  page  653  for  record. 

6a.  Natural  cast  of  the  exterior  of  a  ventral  valve  from  Locality  2i,  Middle  Cambrian  limestone  of  Division 
lbs  on  Hanford  Brook,  .St.  John  County,  New  Brunswick.     U.  S.  Nat.  Mus.  Cat.  No.  .56638a. 

6b.  A  ventral  valve  with  a  cast  of  the  exterior  of  a  dorsal  valve  beside  it.  Associated  with  the  specimen  repre- 
sented by  figure  6a.     V.  S.  Nat.  Mus.  Cat.  No.  ■56638b. 

Acrothele  avia  Matthew  (p.  634). 

[PI.  LXII,  fiys.  1,  la-k.] 

Figure  7.  Exterior  of  a  ventral  \al\e  from  Locality  344b,  Middle  Cambrian  shales  of  Division  E3d  of  Matthew's 
Etcheminian,  Dugald  Brook,  Cape  Breton,  Nova  Scotia,  University  of  Toronto,  Canada.  Speci- 
men figured  by  ilatthew  [1902b,  PI.  XVII,  fig,  2a]. 

7a,  Interior  of  a  broken  ventral  valve  from  Locality  13n',  Middle  Cambrian  shales  of  Division  E3e  of  Matthew's 
Etcheminian,  Dugald  Brook,  Cape  Breton,  Nova  Scotia,  Univer-iity  of  Toronto,  Canada.  Type 
specimen,  figured  by  Matthew  [1899b,  PI,  III,  fig.  Ic], 

7b.  Interior  of  a  dorsal  valve  from  the  locality  represented  by  figure  7a.  University  of  Toronto,  Canada. 
Specimen  figured  by  Matthew  [1899b,  PI.  Ill,  fig.  If]. 


PLATE    LXII. 


207 


PLATE  LXII. 

c.  Area.  j.  Anterior  lateral  muscle  scar, 

cl.  Cardinal  scar.  k.  Middle  lateral  muscle  scar. 
F'.  Cast  of  foraminal  tube.  1.  Outside  lateral  muscle  scar, 

h.  Central  muscle  scar.  vs.  Vascular  sinus. 

AcROTHELE  AVI  A  ]\Iatthew  (p.  6.34). 

[Pi.  LXI.  figs.  r.  7a-l).l 

Figure  1.  Top  view  of  a  typioal  lonii  of  ilio  ventral  valve  from  Locality  13n',  Middle  Cambrian  sand.stones  of  Dhdsion 
E3e  of  Matthew's  section,  Diigald  Brook.  Cape  Breton,  Nova  Scotia.     U.  S.  Nat.  Mus.  Cat.  No.  .56.598a. 

la.  To])  view  of  a  ventral  valve  nearly  circular  in  outline  from  Locality  13d",  Mid<lle  Cambrian  sandstone.?  10 
feet  l)elow  top  of  Divi.sion  E2a  of  Matthew's  section,  Dugald  Brook,  Cape  Breton,  Xova  Scotia.  L".  S. 
Xat.  Mus.  Cat.  .\o.  SGGOla. 

lb.  Laterally  compressed  ventral  valve  from  Locality  131',  Middle  Cambrian  sandstones  of  Division  E3a  on 
Dugald  Brook.  Cape  Breton,  Nova  Scotia.     V.  S.  Xat.  Mus.  Cat.  No.  51970a. 

Ic.  Partly  exfoliated  ventral  valve  from  Locality  13m,  Middle  Cambrian  sandstones  of  Division  E3f  on 
Gillis  Brook,  Cape  Breton.  Xova  .'^cotia.  T'.  S.  Xat.  Mtis.  Cat.  X'o.  56596a.  The  surface  of  this 
specimen  is  enlarged  in  figure  Ij. 

Id.  E.xf(jliated  ventral  valve  (locality  unknown).     L'niversity  of  Toronto.  Canada. 

le.  Fragment  of  the  interior  of  a  ventral  valve  associated  with  the  specimen  represented  by  figure  1  L".  S. 
Xat.  Mus.  Cat.  Xo.  56598b. 

If.  Cast  of  interior  of  dorsal  valve,  from  Locality  13n,  Middle  I'amlMian  sandstones  of  Division  E3f  of  Mat- 
thew's section,  Dugald  Brook,  Cape  Breton,  Xova  Scotia.     L'.  S.  Xat.  Mus.  Cat.  Xo.  56597a. 

Ig.  Interior  of  dorsal  valve  associated  with  the  specimen  represented  by  figure  Ic.  I'.  S.  Xat.  Mus.  Cat.  Xo. 
565961). 

Ih.  Interior  of  a  compres.sed  dorsal  valve  placed  with  tlie  specimens  from  Locality  13m;  tlie  exact  locality  is, 
however,  unknown.     V.  S.  Xat.  Mus.  Cat.  Xo.  56596c. 

li.  Exfoliated  dorsal  valve  from  Locality  344b,  Middle  Cambrian  shales  of  Division  E3d  of  Matthew's 
Etcheminian,  Dugald  Brook,  Cape  Breton,  Xova  Scotia.  University  of  Toronto.  Canada.  Specimen 
figured  by  Matthew  [1902b,  PI.  XVII.  fig.  21)]. 

Ij.  Enlargement  of  a  portion  of  the  surface  of  the  specimen  represented  Ijy  figure  Ic. 

Ik.  Posterior  portion  of  a  ventral  valve  showing  the  apex.  Associated  with  the  specimen  represented  by- 
figure  lb.     U.  S.  Xat.  Mus.  Cat.  Xo.  51970b. 

AcROTHELE    PRIMA    (MattllOW)    (]).  6.l3). 
[PI.  LXI.flgs.  i',.(ja-b.] 

Figure  2.  Partly  exfoliated  ventral  valve  from  Locality  13t,  Middle  Camlirian  shaly  sandstones  of  Division  Elb  on 
Dugald  Brook,  Cape  Breton,  Xova  Scotia.     U.  S.  Xat.  Mus.  Cat.  Xo.  5200')a. 

AcROTHELE  PROLES  Matthew  (p.  654). 

Figure  3.  Exterior  of  a  slightly  compressed  ventral  valve  from  Locality  13m,  Middle  Cambrian  shaly  sandstones  f>f 

Division  E3f  on  Gillis  Brook,  Cape  Breton,  Xova  Scotia.     V.  S.  Xat.  Mus.  Cat.  Xo.  52011a. 
3a.  Portion  of  a  dorsal  valve  associated  with  the  specimen  represented  by  figure  3.     V.  S.  Xat.  Mus.  Cat. 

Xo.  52011b. 
31).  Interior  of  a  fragmentary  ventral  valve  associateil  with  the  specimen  repre.sented  by  figiu'e  3.     I".  S.  Xat. 

Mus.  Cat.  Xo.  520lic. 
3c.  Interior  of  a  small  slightly  distorted  veiilial  valve  a.^sociated  with  the  specimen  represented  by  figure  3. 

U.  S.  Xat.  Mus.  Cat.Xo.  5201  Id. 
3d.  Partly  exfoliated  dorsal  valve  as.sociated  with  the  specimen  iciirescntcil  by  figure  3.     I".  S.  Xat. Mus.  Cat. 

Xo.  5201  le. 
3e.  Partly  exfoliated  dorsal  valve,  showing  va.scular  markings  on   the  inner  layers  of  the  shell.     Locality 

13n.  Middle  Cambrian  .shaly  sandstones  of  Di\Tsion  E3f  on  Dugald  Brook,  Cape  Breton,  Xova  Scotia. 

U.  S.  Xat.  Mus.  Cat.  Xo.  52012a. 
208 


U.  S.  GEOLOGICAL  SURVEY 


MONOGRAPH   LI     PL.  LXII 


•FRANCES  WIE3EB  DEL. 


HELIOTYPE  CO..  80ST0N. 


PLATE  LXII.  209 

AcROTHELE  PROLES  Matthew — Continued. 

Figure  4.  A  cast  of  the  cxlerior  of  tlio  ventral  valve,  preserving  a  portion  of  the  shell.  From  Locality  13m, 
Middle  Cambrian  sandstone  of  Division  E3f  of  Matthew's  Etcheminian,  Oillis  lirook,  Cape  Breton, 
Nova  Scotia.  University  of  Toronto,  Canada.  Type  specimen,  figured  bv  Matthew  [1902b,  PI. 
XVII,  fig.  3a]. 
4a.  Fragment  of  the  interior  of  a  dorsal  valve  (locality  unknown).  Universit)'  of  Toronto,  Canada.  The 
specimen  from  which  this  figure  is  drawn  can  not  be  identified  with  any  of  the  figures  given  bv  Mat- 
thew [1902b,  PI.  XVII,  fig.s.  3a-e]. 

BoTSFORDiA  PULCHRA  Matthew  (p.  607). 

Figure  5.  Exterior  and  side  view  of  ventral  valve.     (See  note  following  fig.  5  1.) 

5a.  Exterior  of  ventral  valve,  with  reticulate  surface  ornamentation  on  young  .sliell  only.     U.  S.  Nat.  Mus, 

Cat.  No.  52047a. 
5b.  Exterior  of  ventral  valve.     U.  S.  Nat.  Mus.  Cat.  No.  52047b. 
5c.  Exterior  and  side  view  of  dorsal  valve.     (See  note  following  fig.  5  1.) 
5d.  Exterior  of  dorsal  valve.     U.  S.  Nat.  Mus.  Cat.  No.  52047c. 
5e.  Exterior  of  ventral  valve.     U.  S.  Nat.  Mus.  Cat.  No.  52047d. 
5f  and  5f'.  Top  and  back  views  of  a  ventral  valve.     U.  S.  Nat.  Mus.  Cat.  No.  52047e. 
5g.  Cast  of  the  interior  of  a  ventral  valve.     U.  S.  Nat.  Mus.  Cat.  No.  52047f. 

5h  and  5j.  Casts  of  the  interior  of  dorsal  valves.     U.  S.  Nat.  Mus.  Cat.  Nos.  52047g  and  52047h,  respectively. 
5k.  Portion  of  surface,  greatly  enlarged,  of  the  specimen  represented  by  figure  51.     U.  S.  Nat.  Mus.  Cat. 

No.  52047i. 
51.  Exterior  of  a  dorsal  valve.     U.  S.  Nat.  Mus.  Cat.  No.  52047i. 

The  specimens  represented  are  all  from  Locality  2y,  Middle  Camlirian  sandstone  on  Catons  Island,  Long  Reach, 
St.  John  River,  New  Brunswick,  with  the  possible  exception  of  the  specimens  represented  by  figures  5  and  5c,  which 
can  not  now  be  located  in  the  collections  of  the  United  States  National  Museum.    These  figures  may  have  been 
drawn  from  specimens  loaned  to  the  Museum  and  since  returned. 
62667°— VOL  51,  pt  2—12 14 


PLATE    LXIII. 


211 


PLATE  LXIII. 


cl.  Cardinal  scars. 

f.  Flexure  line  of  area. 
F'.  Cast  of  foramina!  tube, 
h.  Central  muscle  scar. 

i.  Transmedian  muscle  scar. 


j.  Anterior  lateral  muscle  scar, 
k.  Middle  lateral  muscle  scar. 
1.  Outside  lateral  muscle  scar, 
p.  I'edicle  furrow. 
s.  Median  septum. 


AcBOTHELE  CERATOPYGARr.M  (Broggcr)  (p.  640). 

Figures  1  and  la.  Top  and  side  views  of  a  ventral  valve,  the  type  .specimen,  from  Locality  323h,  pa.ssagc  beds 
between  the  Upper  Cambrian  and  the  Or(lo\-ician,  Ceratopyge  limestone  at  Vestfossen,  10  miles  south- 
southwest  of  Christiania,  Norway.  Copied  from  Brogger's  figures  [1882,  PI.  X,  figs,  la  and  ]b]  of 
Discina  (Acrotrcta  ?)  ceratopyyaram. 
lb  and  Ic.  Top  and  side  \dews  of  an  exfoliated  ventral  \ah"e  as.sociated  with  the  valve  represented  by  figures 
1  and  la.     V.  S.  Nat.  Mus.  Cat.  No.  51977a. 

ACROTHELE    BORGHOLMEXSIS    Walcott    (p.  639). 

Figures  2  and  2a.  Top  and  side  views  of  a  partly  exfoliated  \entral  valve,  the  type  specimen,  from  Locality  310d, 
Upper  Cambrian  Ceratopyge  slate  at  Borgholm,  Oeland  Island,  Sweden.     V .  S.  Xat.  Mus.  Cat.  No. 
51974a.     Copied  from  Walcott  [1908d,  PI.  VIII,  figs.  12  and  12']. 
2b.  Interior  of  a  small  dor.^al  valve  associated  with  the  specimen  represented  by  figun  s  2  and  2a.     I'.  S.  Xat. 
Mus.  Cat.  No.  51974b. 

ACROTIIELE?    MINUTA    Walcott    (p.  650). 

FiGUiiE  3.  Exterior  view  of  a  partly  exfoliated  dorsal  valve,  the  type  specimen,  from  Localily  C6,  Middle  Cambrian 
shaly  limestone  2.5  miles  southwest  of  Yenchuang,  J-^intai  district ,  Shantung,  China.  U.  S.  Nat.  Mus. 
Cat.  No.  52519a. 


AcROTHELE    RARA    Willcott     (p.  6.55). 

Figure  4.  Cast  of  interior  of  a  ventral  valve,  the  type  specimen,  from  Locality  C57,  Middle  Cambrian  shale  3  miles 
south  of   Kaokiapu,  Sintai  district.  Shantung,  China.     U.  S.  Nat.  Mus.  Cat.  No.  52518a. 
4a.  Cast  of  interior  of  a  dorsal  valve  associated  with  the  shell  represented  by  figure  4.     I'.  S.  Nat.  Mus.  Cat. 
No.  52518b. 

AcROTHELE   sp.  lindt.  <t  "Willcott    (p.  662). 

Figure  5.  Top  and  side   view  of   type  specimen  from  Locality  319b.    Lower  Cambrian   limestone   at  St.  Simon, 
Quebec,  Canada.     V .  S.  Nat.  Mus.  Cat.  No.  52032a. 

ACROTIIELE    COLLENI    Walcott    (p.  640). 
IText  figs.  oo.V-E,  p.  041.] 

Figures  (i  ami  6'.  Top  and  side  views  of  the  type  .specimen,  a  veiKral  vahr,  from  Localily  4q,  Middle  Cambrian 
.shale  near  Gordon  Mountain,  Ovando  quadrangle,  Montana.     V .  S.  Nat.  Mus.  Cat.  No.  51973a. 
6a  and  Ga'.  Top  and  back  views  of  the  posterior  portion  of  a  ventral  valve  associated  with  the  shell  rejjre- 

sented  by  figure  6.     U.  S.  Nat.  Mus.  Cat.  No.  51973b. 
6b.  Exterior  of  dorsal  valve  associated  with  the  shell  represented  by  figure  6.     L.  S.  Xat.  Mus.  Cat.  Xu. 
51973c. 
212 


U.  S.  GEOLOGICAL  SURVEY 


MONOGRAPH   LI     PL.  LXIII 


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FRANCES  WIESER  DEL 

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PLATE  LXIII.  213 

Helmersenia  ladogensis  (Jeremejow)  (p.  .368). 

Figure  7.  Extorior  view  and  side  outline  of  a  ventral  valve  from  Locality  336p,  li|i]icr  Camlirian  sandstone  at  Kunitz, 

Pskow,  Russia.     U.  S.  Nat.  Mus.  Cat.  No.  51941a. 
7a.  Exterior  of  a  transverse  dorsal  valve  from  Locality  336o,  Upper  Cambrian  sandstone  at  Koporje,  St.  Peters- 
burg, Russia.     U.  S.  Nat.  Mus.  Cat.  No,  51940a. 
7b  and  7b'.  Exterior  of  a  rounded  ventral  valve,  and  side  outline,  a.ssociated  willi  the  specimen  represented 

by  figure  7a.     U.  S.  Nat.  Mus.  Cat.  No.  51940b. 
7c.  Posterior  view  of  a  donsal  valve  from  Locality  336q,  Upper  Cambrian  .sandstone  near  Ladoga,  Government 

of  St.  Petersburg,  Ru.«.sia.     Copied  from  Pander  [1861,  PI.  II,  fig.  2f] 
7d.  Interior  view  of  a  ventral  valve,  the  type  specimen,  associated  with  (he  valve  represented  by  figure  7c. 

Copied  from  Pander  [1861,  PI.  II,  fig.  2d]. 
7e.  Exterior  of  a  dorsal  ?  valve  associated  with  the  specimen  represented  liy  figure  7a.     IT.  S.  Nat.  Mus.  Cat. 

No.  51940c. 
7f.  Interior  of  a  ventral?  valve  a.ssociated  ■sWth  the  specimen  represented  by  figure  7a.     U.  S.  Nat.  Mus.  Cat. 

No.  51940d. 

Oboiat.s  (Westonia)  elongatus  Wiilcott  (p.  4.59). 

Figure  8.  Compressed,  exfoliated  ventral  valve.     U.  S.  Nat.  Miis.  Cat.  No.  51722b. 

8a.  Exfoliated  interior  of  a  ventral  valve,  the  type  specimen,     li.  S.  Nat.  Mus.  Cat.  No.  51722a.     Copied 

from  Walcott  [1908d,  PI.  VII,  fig.  12]. 
8b  and  8c.  Exfoliated  interiors  of  dorsal  valves.     U.  S.  Nat.  Mus.  Cat.  Nos.  51722c  and  51722d,  respectively. 
8d.  Enlargement  of  a  portion  of  the  matrix  of  the  outer  surface  of  the  dorsal  valve  represented  by  figure  8b. 

The  spaces  inclosed  by  the  obliciue  lines  are  not  so  convex  as  represented  on  the  figure.     U.  S.  Nat. 

Mus.  Cat.  No.  51722c. 

The  specimens  represented  are  all  from  Locality  105x,  Middle  Orduviciaii  shales  in  Wasatch  Canyon,  north  of 
Brigham,  Boxelder  County,  Utah. 

Obolus  (Westonia)  notchensis  Walcott  (p.  46.3). 

Figure  9.  Fragment  of  a  ventral  valve,  the  type  specimen,  preserving  a  portion  of  the  outer  surface,  from  Locality 
lost.  Lower  Ordovician  limestone  on  Notch  Peak,  House  Range,  Utah.  XJ.  S.  Nat.  Mus.  Cat. 
No.  51731a.     Copied  fr..m  Walcott  [1908d,  PI.  VII,  fig.  13]. 

Obolus  (Fordinia)  perfectxis  Walcott  (p.  429). 

Figures  10  and  10'.  Exterior  and  side  \'iew  of  a  ventral  valve.     U.  S.  Nat.  Mus.  Cat.  No.  51947b. 

10a.  Interior   of  a  ventral  valve,   the  type  specimen.    U.  S.  Nat.  Mus.  Cat.  No.  51947a.    Copied  from 

Walcott  [1908d,  PI.  VII,  fig.  16]. 
10b.  Exterior  and  side  Aaew  of  a  dorsal  valve.     U.  S.  Nat.  Mus.  Cat.  No.  51947c. 
10c  and  lOd.  Interiors  of  dorsal  valves.     V.  S.  Nat.  Mus.  Cat.  Nos.  51947d  and  51947e,  respectively. 

The  specimens  represented  are  all  from  Locality  30n,  Middle  Cambrian  Weeks  limestone,  in  Weeks  Canyon, 
House  Range,  Utah. 


1 


PLATE    LXIV. 


215 


PLATE  LXIV. 


a.  Outer  lateral  space  of  area. 
cl.  Cardinal  scars. 

f.  Fle.xure  line  of  area, 
fa.   False  area, 
p.  False  pedicle  groove. 


h.  Central  scars. 

s.  Median  septum  or  ridge. 

V.  Visceral  area. 
vs.  Main  vascular  sinus. 
.x".  Cast  of  apical  callosity. 


ACROTRETA    ATTENUATA    Meek  (p.  675). 
[PI.  LXXIX,  figs.  6  and  6a.J 

Figures  1,  1',  1",  and  la,  la',  la".  Top  views  with  side  and  back  views  of  ventral  valves  in  the  material  upon  which 

Meek  founded  the  species.     From  Locality  302,  Middle  Cambrian  limestone  east  of  West  Gallatin 

(Gallatin)  River,  above  Gallatin,  Montana.     U.  S.  Nat.  Mus.  Cat.  Nos.  7867a  and  7867b,  respectively. 

Figure  1  represents  the  type  specimen, 
lb,  lb',  lb",  and  Ic,  Ic',  Ic".    Top,  side,  and  back  views  of  two  ventral  valves  from  Locality  166a,  Middle 

Cambrian  limestones  north  of  East  Gallatin  River,  near  Hillsdale,  Montana.     U.  S.  Nat.  Mus.  Cat. 

Nos.  52063a  and  52063b,  respectively. 
Id,  Id',  Id";  le,  le',  le";  and  If,  If,  If".  Top,  side,  and  back  views  of  three  ventral  valves,  from  Locality  4n, 

Middle  Cambrian  lunestone  in  the  divide  at  the  head  of  Jackson  Creek,  Teton  Mountains,  Wyoming. 

U.  S.  Nat.  Mus.  Cat.  Nos.  52067a,  52067b,  and  52067c,  respectively. 
Ig,  Ig',  and  Ig".  Top,  side,  and  back  views  of  a  ventral  valve  from  Locality  159,  Middle  Cambrian  limestone 

on  the  north  side  of  West  Gallatin  (Gallatin)  River,  Montana.     U.  S.  Nat.  Mus.  Cat.  No.  52064a. 
Ih.  Dorsal  valve  associated  with  the  ventral  valves  represented  by  figiu'es  1  and  la.     U.  S.  Nat.  Mus.  Cat. 

No.  7867c. 
li.  Interior  of  ventral  valve,  showing  base  uf  apical  callosity,  vascular  sinuses,  and  cardinal  scars.     From 

Locality  lOy,  Middle  Cambrian  Marjum  limestone,  southeast  of  Maxjum  Pass,  House  Range,  Utah. 

U.  S.  Nat.  Mus.  Cat.  No.  52070a. 
Ij,  Ik,  and  1 1.  Top,  back,  and  side  views  of  a  cast  of  the  interior  of  a  ventral  valve  associated  with  the  shell 

represented  by  figure  li.     U.  S.  Nat.  Mus.  Cat.  No.  52070b. 
Im.  Interior  of  a  dorsal  valve  associated  with  the  specimen  represented  by  figiu-e  li.     U.  S.  Nat.  Mus.  Cat. 

No.  52070c. 
In.  Interior  of  a  dorsal  valve  from  Locality  3s,  Middle  Cambrian  shales  of  the  Wheeler  formation,  east  of  Ante- 
lope Springs,  House  Range,  Utah.     U.  S.  Nat.  Mus.  Cat.  No.  52069a. 
lo.  Exterior  of  a  dorsal  valve  associated  with  the  specimen  represented  by  figtire  In.     U.  S.  Nat.  Mus.  Cat. 

No.  52069b. 

AcROTRETA    DEFINITA    Walcott  (p.  683). 

Figures  2,  2',  2";  2a,  2a',  2a";  and  2b,  2b',  2b".  Top,  side,  and  back  views  of  tj-pical  forms  of  the  ventral  valve. 

U.  S.  Nat.  Mus.  Cat.  Nos.  35270a,  35270b,  and  35270c,  respectively. 
2c,  2c',  and  2c".  Cast  of  the  interior  of  a  ventral  valve,  the  type  specimen,  with  back  and  side  views. 

U.  S.  Nat.  Mus.  Cat.  No.  35270d. 
2d,  2d',  and  2d".  Top,  back,  and  side  views  of  the  cast  of  the  interior  of  a  dorsal  valve,  showing  the  area, 

cardinal  scar,  etc.,  with  unusual  clearness.     U.  S.  Nat.  Mus.  Cat.  No.  35270e. 
2e,  2f,  and  2g.  Exterior  views  of  three  dorsal  valves,  illustrating  variation  in  outline.     U.  S.  Nat.  Mus.  Cat. 

Nos.  35270f,  35270g,  and  35270h,  respectively. 

The  specimens  represented  by  figures  2,  2a-g  are   from  Locality  163,  Middle  Cambrian  Spence  shale  member  of 
Ute  limestone,  Spence  Gulch,  15  miles  west  of  Montpelier,  Idaho. 

Figures  3,  3a,  and  3b.  Top,  back,  and  side  views  of  a  cast  of  a  ventral  valve  from  Locality  55,  Middle  Cambrian 
Eldorado  limestone  in  New  York   Canyon,  Eureka  district,  Nevada.     U.  S.  Nat.  Mus.  Cat.  No. 
35271a. 
216 


U.  S.   GEOLOGICAL  SURVEY 


MONOGRAPH   LI     PL.  LXIV 


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FRANCES  WIESEft  OEL. 


MELIOrvPE    CO    ROSTOH 


PLATE   LXV. 


217 


PLATE  LXV. 


a.  Area. 

a'.  Outer  lateral  space  of  area, 
ol.  Cardinal  scars, 
fa.  False  area, 
fp.  False  pedicle  groove. 


h.  Central  scars. 

s.  Median  septum  or  ridge. 
vs.  Main  vascular  sinus. 
x".  Cast  of  apical  callosity. 


ACROTRETA    IDAHOENSIS    Walcott    (j).  687). 
[Fl.  LXVIII,  figs.  2,  2a-g.l 

Figures  1,  V,  1";  la,  la',  la";  lb,  IV,  lb";  and  Ic,  Ic',  Ic".  Top.  side,  and  back  views  of  tj'pical  forms  of  the  ventral 
valve.  U.  S.  Nat.  Mus.  Cat.  Nos.  52091a,  52091b,  52091c,  and  52091d,  respectively.  Figure  lb  repre- 
sents the  type  specimen. 

Id,  Id',  and  Id".  Top,  back,  and  side  views  of  cast  of  the  interior  of  a  ventral  valve.  V.  S.  Nat.  Mus.  Cat. 
No.  52091e. 

le.  Cast  of  the  interior  of  a  dorsal  valve.     U.  S.  Nat.  Mus.  Cat.  No.  52091f. 

If.  Interior  of  a  dorsal  valve.    U.  S.  Nat.  Mus.  Cat.  No.  52091g. 

Ig.  Natural  cast  of  tlie  interior  of  the  dorsal  valve  represented  by  figure  If.    U.  S.  Nat.  Mus.  Cat.  No.  52091g. 

Ill  and  li.  Exteriors  of  two  dorsal  valves.    U.  S.  Nat.  Mus.  Cat.  Nos.  52091h  and  520911,  respectively. 

The  specimens  represented  are  all  from  Locality  5c,  Upper  Cambrian  limestone  in  Twomile  Canyon,  2  miles  south- 
east of  Malade,  Idaho. 

AcROTRETA  ATTENUATA  var.  Walcott  (p.  676). 

Figures  2,  2',  and  2".  Top,  side,  and  back  views  of  a  specimen  with  a  more  distinctly  marked  false  area  than  usually 
occurs  in  typical  A.  attenuata.  Associated  with  the  type  of  that  species  in  Locality  302,  Middle  ( 'aui- 
brian  limestone  east  of  West  Gallatin  (Gallatin)  River  above  Gallatin,  Montana.  V.  S.  Nat.  Mus. 
Cat.  No.  52071a. 

AcROTRETA    KUTORGAI    Walcott   (p.  692). 
[Te.\t  fig.  58,  p.  693.] 

Figures  3,  3',  3",  and  3a,  3a',  3a".  Top,  back,  and  side  \'iews  of  the  exterior  of  two  ventral  valves  from  Locality  139a, 

Middle  Cambrian  limestone  near  Chepultepec,  Jefferson  County,  Alabama.     U.  S.  Nat.  Mus.  Cat. 

Nos.  58305a  and  58305b. 
3b,  31)'.  3b",  and  3c,  3c',  3c".  Top,  back,  and  side  views  of  casts  of  the  interior  of  Aentral  valves.     U.  S.  Nat. 

Mus.  Cat.  Nos.  35277a  and  35277b,  respectively.     Figure  3b  represents  the  type  specimen. 
3d.  Side  \'iew  of  cast  of  ventral  valve,  showing  cast  of  pedicle  tube.     V.  S.  Nat.  Mus.  Cat.  No.  35277c. 
3e.  Cast  of  pedicle  tube,  showing  lines  of  shell  growth.     U.  S.  Nat.  Mus.  Cat.  No.  35277d. 
3g.  View  into  cast  of  ventral  valve,  with  cast  of  area  of  dorsal  valve  in  position.     U.  S.  Nat.  Mus.  Cat.  No. 

35277e.     This  specimen  is  tipped  so  as  to  show  the  cast  of  the  areas  of  both  the  ventral  and  dorsal 

valves  in  text  figure  58,  page  692. 
3h,  31,  3j,  and  3k.  Casts  of  interiors  of  dorsal  valves,  illustrating  variation  in  median  ridge,  muscle  scars,  etc. 

U.  S.  Nat.  Mus.  Cat.  Nos.  35277f,  35277g,  35277h,  and  352771,  respectively. 

The  specimens  represented  by  figtires  31>-k  are  all  from  Locality  90x,  Middle  Cambrian  siliceous  nodules  in  the 
Conasauga  shale,  Coosa  Valley,  Cherokee  County.  Alaliania. 

AcROTRETA  RUDis  Walcott  (j).  702). 

(I'l.  LXXV,  fig.  1.) 

Figure  3f.  Ventral  valve,  the  tj^jc  specimen,  flattened  in  the  shale  of  Locality  101a,  Middle  Cambrian.  3.5  miles  south- 
west of  KoKcrsville.  Hawkins  County,  Teimessee.     U.  S.  Nat.  Mus.  Cat.  Xo.  52111a.     Copied  from 
\\ulcott  [1908d,  PI.  IX,  fig.  5]. 
218 


U.  S.   GEOLOGICAL  SURVEY 


MONOGRAPH   LI     PL.   LXV 


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PLATE  LXV.  219 

ACROTRETA    IDAHOENSIS    ALTA    Walcott  (p.  689). 

Figures  4,  4',  and  4".  Top,  side,  and  Ijack  views  of  a  ventral  valve  from  Locality  15d,  Upper  Cambrian  limestone  near 
Cave  Spring,  Fish  Spring  Range,  Utah.     U.  S.  Nat.  Mus.  Cat.  No.  52099a. 

4a,  4a',  and  4a".  Top,  side,  and  Ixick  views  of  a  ventral  valve  from  Locality  88,  Middle  Cambrian  shaly  lime- 
stone in  either  New  York  or  Secret  Canyon,  Eureka  district,  Nevada.  U.  S.  Nat.  Mus.  Cat.  No. 
35273a.    Type  specimen,  figured  by  Walcott  [1884b,  PI.  I,  fig.  la], 

4b.  Dorsal  valve  associated  with  the  specimen  represented  by  figure  4.     U.  S.  Nat.  Mus.  Cat.  No.  52099b. 

ACROTRETA    IDAHOENSIS    SULCATA    Walcott   (p.  690). 

Figures  5,  5',  and  5".  Top,  side,  and  back  views  of  a  ventral  valve,  the  type  specimen,  with  the  apex  broken  off. 
From  Locality  322a,  Middle  Cambrian  Langston  limestone  near  Paris,  Idaho.  U.  S.  Nat.  Ma'?.  Cat. 
No.  35275a. 

AcROTRETA    EMMONSI   Walcott  (p.  684). 

Figure  6.  Cast  of  the  interior  of  a  dorsal  valve,  the  type  specimen,  from  Locality  35a,  Lower  Cambrian  limestone  on 
Bald  Mountain,  Washington  County,  New  York,  showing  vascular  markings  and  muscle  scars. 
U.  S.  Nat.  Mus.  Cat.  No.  52087a. 


PLATE    LXVI. 


221 


PLATE  LXVI. 

a'.  Outer  lateral  spaoe  of  area.  s.  Median  septum  or  ridge, 

cl.  Cardinal  scar.  vs.  Main  vascular  sinus, 

fp.  False  pedicle  groove.  x".  Cast  of  apical  callosity, 
h.  Central  muscle  scar. 

AcROTRETA  GEMMA  Billings  (p.  6S5). 

Figures  1,  1',  1",  and  la,  la',  la".  Top,  side,  and  back  views  of  two  ventral  valves  from  Locality  314d,  Lower  Ordovi- 
cian  limestone  4  miles  northeast  of  Portland  Creek,  Newfoundland.     Mus.  Geol.  Survey  Canada. 
Figure  1  may  be  taken  as  the  type, 
lb.  Enlargement  of  the  apex  anil  foraminal  opening  of  a  ventral  valve  associated  with  (he  specimeDS  repre- 
sented by  figures  1  and  la. 

Figures  1,  la-b  are  drawn  from  the  specimens  illustrated  Ijy  Billings  [1865,  figs.  201b,  d,  c,  and  f]. 

AcROTRETA  ovALis  Walcott  (p.  699). 

Figures  2,  2a,  and  2b.  Top,  side,  and  back  views  of  the  type  specimen,  a  ventral  valve,  from  Locality  314d,  Lower 
Ordovician  limestone  4  miles  northeast  of  Portland  Creek,  Newfoundland.     Mus.  Geol.  Survey  Canada. 

AcROTRETA    GEMMULA    MatthcW  (p.  686). 

[PI.  LXXVII,  figs.  5,5a-f.l 

Figures  3,  3',  and  3".  Top,  back,  and  side  views  of  the  outer  surface  of  a  ventral  valve  (locality  unknown).  Univer- 
sity of  Toronto,  Canada. 

3a.  Top,  back,  and  side  \dews  of  the  cast  of  the  interior  of  a  ventral  valve  in  which  the  ca.«t  of  the  ba.se  of  the 
foraminal  tube  is  unusually  large.  Locality  301a,  Middle  Cambrian  sandstones  in  Divi.sion  IbS  of 
Matthew  on  Hanford  Brook,  St.  John  County,  New  Brunswick.  University  of  Toronto,  Canada. 
Type  specimen,  figured  by  Matthew  [1894,  PI.  XVI,  fig.  2a]. 

3b  and  3c.  Cast  and  interior  of  a  dorsal  valve  from  the  locality  represented  by  figure  3a.  University  of 
Toronto,  Canada.     Specimen  figured  by  Matthew  [1894,  PI.  XVI,  fig.  2b]. 

AcROTRETA    SAGITTALIS    MAGNA    (Matthew)    (p.  706). 

Figures  4  and  4a.  Top  and  side  vaews  of  a  cast  of  the  interior  of  a  ventral  valve  from  Locality  2s,  Middle  Cambrian 

limestone  at  Hastings  Cove,  northeast  of  St.  John,  New  Brunswick.     University  of  Toronto,  Canada. 

Specimen  figured  by  Matthew  [1897b,  PI.  I,  fig.  lb]  as  Linnarssonia  helti  magna. 
4b.  Cast  of  the  interior  of  a  dorsal  valve  from  the  locality  represented  by  figure  4.     I'niversity  of  Toronto, 

Canada.     Type  specimen,  figiu'ed  by  Matthew  [1897b,  PL  I,  fig.  la]  as  Linnarssonia  belli  magna. 
4c,  4c',  and  4c".  Top,  back,  and  side  views  of  a  small  well-preserved  ventral  valve  from  Locality  2  1,  Middle 

Cambrian  limestone  on  Hanford  Brook,  St.  John  Coimty,  New  Brunswick.     U.  S.  Nat.  Mus.  Cat. 

No.  35284a. 
4d.  Interior  of  a  partly  crushed  ventral  valve  associated  with  the  shell  represented  by  figure  4c.     U.  S. 

Nat.  Mus.  Cat.  No.  35284b. 
4e  and  4f .  Interior  of  a  dorsal  valve  and  natural  cast  of  same  associated  with  the  shell  represented  by  figure  4c. 

U.  S.  Nat.  Mus.  Cat.  Nos.  35284c  and  35284d,  respectively. 

ACROTKETA    GRACIA    Walcott   (p.  687). 

Figures  5,  5',  and  5".  Top,  back,  and  side  views  of  a  ventral  valve.     U.  S.  Nat.  Mus.  Cat.  No.  35272a. 

5a,  5a',  and  5a".  Top,  back,  and  side  xnews  of  a  cast  of  a  ventral  valve,  the  type  specimen.    U.  S.  Nat.  Mus. 

Cat.  No.  35272b. 
5b.  Cast  of  part  of  the  interior  of  a  dorsal  valve.     U.  S.  Nat.  Mus.  Cat.  No.  35272o. 
5c  and  5c'.  Top,  side,  and  back  views  of  a  cast  of  a  dorsal  valve.     U.  S.  Nat.  Mus.  Cat.  No.  35272d. 
5d.  Cast  of  the  exterior  of  a  dor.sal  valve,  with  a  portion  of  the  posterior  part  of  the  shell.     U.  S.  Nat.  Mus. 
Cat.  No.  35272e. 
The  specimens  represented  arc  all  from  Locality  2s,  Middle  Cambrian  limestone  at  Hastings  Cove,  on  Kennebecasis 
Bay,  northeast  of  St.  John,  New  Brunswick. 
222 


U.  S.   GEOLOGICAL  SURVEY 


MONOGRAPH   LI     PL.  LXVI 


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PLATE  LXVI.  223 

AcROTRETA  CON  VEX  A  Walcott  (p.  682). 

Figure  6.  Cast  of  the  interior  of  a  ventral  valve,  the  type  specimen,  from  Locality  3n,  Upper  Cambrian  sandstones 

on  Salmon  River,  Gillis  Hill,  Cape  Breton,  Nova  Scotia.     U.  S.  Nat.  Mus.  Cat.  No.  35268a. 
6a.  Cast  of  the  interior  of  a  dorsal  valve  associated  with  the  shell  represented  by  figure  6.     U.  S.  Nat.  Mus.  Cat. 

No.  35268b. 
6b,  6b',  and  6b".  Top,  side,  and  back  views  of  the  cast  of  a  ventral  valve  from  Locality  lOi,  Upper  Cambrian 

shale  on  Barachois  River,  just  north  of  the  Boisdale  Road,  Cape  Breton,  Nova  Scotia.     U.  S.  Nat. 

Mus.  Cat.  No.  52084a. 
6c.  Cast  of  interior  of  dorsal  valve  from  Locality  lOe,  Upper  Cambrian  shales  on  east  branch  of  Barachois 

River,  north   of  the  crossroad  from  Boisdale  to  Upper  Leitches  Creek,  Cape  Breton,  Nova  Scotia. 

U.  S.  Nat.  Mus.  Cat.  No.  52085a. 

AcROTRETA  BisECTA  Mattliew  (p.  678). 

Figures  7,  7',  and  1" .  Top,  side,  and  back  views  of  a  parJy  exfoliated  ventral  valve.     V .  S.  Nat.  Mus.  Cat.  No. 
,52073a. 
7a,  7a',  and  7a".  Top,  side,  and  back  views  of  cast  of  ventral  valve.     U.  S.  Nat.  Mus.  Cat.  No.  52073b. 
7b.  Interior  of  a  dorsal  valve.     U.  S.  Nat.  Mus.  Cat.  No.  52073c. 
7b'.  Enlargement  of  the  area  of  figure  7b. 

7c.  Cast  of  the  interior  of  a  dorsal  valve  on  which  the  lines  of  growth  about  the  cardinal  scars  are  beau- 
tifully shown.     U.  S.  Nat.  Mus.  Cat.  No.  52073d. 
7d.  Cast  of  the  interior  of  a  dorsal  valve.     U.  S.  Nat.  Mus.  Cat.  No.  52073e. 

The  specimens  represented  by  figures  7,  7a-d  are  from  Locality  3q,  Upper  Cambrian  shale  in  Barachois  Glen, 
south  of  Little  Bras  d'Or  Lake,  Cape  Breton,  Nova  Scotia. 

Figure  7e.  Cast  of  the  interior  of  the  posterior  portion  of  a  ventral  valve  in  which  the  cast  of  the  main  vascular  sinuses 
is  finely  preserved;  also  the  cast  of  the  base  of  the  pedicle  tube.  Locality  lOe,  L'pper  Cambrian  shales 
on  east  branch  of  Barachois  River,  north  of  crossroad  from  Boisdale  to  Upper  Leitches  Creek,  Cape 
Breton,  Nova  Scotia.     U.  S.  Nat.  Mus.  Cat.  No.  52077a. 

ACROTRETA    DEPRESSA  (Walcott)    (p.  683). 

Figures  8  and  8'.  Top,  side  outline,  and  back  view  of  the  type  specimen,  a  cast  of  the  interior  of  a  compressed  ventral 

valve,  from  Locality  14s,  Middle  Cambrian  shaly  limestones  {Ogygopsis  zone)  on  Mount  Stephen, 

British  Columbia.     U.  S.  Nat.  Mus.  Cat.  No.  52086c.     Copied  from  Walcott  [1908c,  PI,  I,  fig.  3c]. 
8a  and  8b.  Casts  of  the  interior  of  two  dorsal  valves  associated  with  the  shell  represented  by  figure  8.     U.  S. 

Nat.  Mus.  Cat.  Nos.  52086a  and  52086b,  respectivelv.     Figure  8a  is  copied  from  Walcott  [1908c,  PL  I, 

fig.  3b]. 
8c,  8c',  and  8c".  Top,  side,  and  back  \-iews  of  a  ventral  valve  occurring  in  the  same  beds  with  the  specimens 

represented  by  figures  8,  8a-b,  but  which  is  very  doubtfully  referred  to  this  species.     U.  S.  Nat. 

Mus.  Cat.  No.  52086d.     Figures  8c  and  8c'  are  copied  from  Walcott  [1908c,  PI.  I,  figs.  3  and  3a, 

respectively]. 


} 


PLATE   LXVII. 


62667°— VOL  51,  pt  2—12 15 


PLATE  LXVII. 


cl.  Cardinal  scar. 

fa.  False  area. 

fp.  False  pedicle  groove. 

h.  Central  muscle  scar. 

1.  Outside  lateral  muscle  scar. 


s.  Median  septum. 

V.  Visceral  cavitj-. 
X.  Foraminal  aperture, 
x'.  Ca.st  of  foraminal  aperture. 


ACROTRETA    MICROSCOPICA    (SllUmaill )    ({).  693). 

Figures  1,  V,  1";  la,  la',  la";  lb,  lb',  lb";  and  Ic,  Ic',  Ic".  Top,  back,  and  side  views  of  the  exterior  of  four  ventral 
valves  illustrating  variations  in  outline,  position  of  the  apex,  etc.  Locality  67,  Upper  Cambrian 
limestone,  on  Tatur  Hill,  northeast  of  BiuTiet,  Burnet  County,  Texas.  V .  S.  Nat.  Mus.  Cat.  Nos. 
52120a,  52120f,  52120b,  and  52120c,  respectively. 

Id,  Id',  and  Id".  Top,  back,  and  side  views  of  a  ventral  valve  from  Locality  70e,  Upper  Cambrian  limestone, 
near  Morgans  Creek,  Burnet  County,  Texas.     L".  S.  Nat.  Mus.  Cat.  No.  52118a. 

le  and  Ig.  Exteriors  of  dorsal  valves  associated  with  the  shells  represented  by  figures  1,  la-c.  U.  S.  Nat .  Mus. 
Cat.  Nos.  52120d  and  52120e,  respectively. 

If  and  Ih.  Exteriors  of  dorsal  valves  associated  with  the  specimen  represented  by  figure  Id.  U.  S.  Nat.  Mus. 
Cat.  No.  5211Sb  and  52118c,  respectively. 

lo,  lo',  and  lo".  Top,  side,  and  back  ^•iews  of  the  cast  of  a  small  ventral  valve  from  Locality  68,  Upper  Cam- 
brian limestone,  on  Packsaddle  Mountain,  Llano  County,  Texas.     L'.  S.  Nat.  Mus.  Cat.  No.  52504a. 

2,  2',  and  2".  Top,  back,  and  side  \-iew8  of  a  ventral  valve  with  an  unusually  well-defined  false  area.  V.  S. 
Nat.  Mus.  Cat.  No.  521193. 

2a,  2a',  and  2a".  Top,  back,  and  side  views  of  a  ventral  valve  which  has  lost  the  apex  and  exposed  the  ft)rami- 
nal  tube.     U.  S.  Nat.  Mus.  Cat.  No.  .52119b. 

2b  and  2c.  Side  \-iews  of  two  elevated  ventral  valves.  V.  S.  Nat.  Mus.  Cat.  Nos.  52119c  and  52119d,  respec- 
tively. 

2d.  Exterior  of  dorsal  valve  with  side  outline.     V.  S.  Nat.  Mus.  Cat.  No.  52119e. 

The  specimens  represented  by  figures  2,  2a-d  are  all  from  Locality  8o,  Upper  Cambrian  limestone,  2  miles  north 
of  Aurum,  Schell  Creek  Range,  White  Pine  County,  Nevada. 


ACROTKETA    MICROSCOPICA    TETONENSIS    Walcott  (p.  694). 


,  Mus. 


FiGTTRES  3,  3',  3";  3a,  3a',  3a";  and  3b,  3b',  3b".  Top,  back,  and  side  views  of  three  ventral  valves.     U.  S.  Nat. 
Cat.  Nos.  352S0a,  352S0b,  and  35280e,  respectively.     Figure  3  represents  the  type  specimen. 
3c  and  3d.  Exterior  \'iews,  and  outlines  showing  convexity,  of  two  dorsal  valves.     V.  S.  Nat.  Mus.  Cat.  Nos. 
35280c  and  35280d,  respectively. 

The  specimens  represented  by  figures  3,  3a-d  are  from  Locality  4e,  Middle  Cambrian  limestones  in  divide  at  the 
head  of  Jackson  Creek,  Teton  Mountains,  Wyoming. 

ACROTRETA    MICROSCOPICA    MISSOTJRIENSIS   Walcott  (p.  694). 

Figures  4,  4',  and  4".  Top,  back,  and  side  views  of  the  type  specimen,  a  vcniral  valve  that  has  been  slightly  com- 
pressed longitudinally,  thus  elevating  it,  also  emphasizing  the  median  furrow  on  the  false  area. 
U.  S.  Nat.  Mus.  Cat.  No.  35728a. 

4a  and  4a'.  Top  and  side  views  of  a  ventral  valve  that  has  been  depressed  by  compression,  the  apex  being 
forced  backward  over  the  false  area.     U.  S.  Nat.  Mus.  Cat.  No.  35278b. 

4b.  Exterior  of  dorsal  valve,  showing  traces  of  radiating  strise  and  numerous  indentations  caused  by  the  fine 
grains  of  sand  in  the  matrix.     V.  S.  Nat.  Mus.  Cat.  No.  35278c. 

The  specimens  represented  are  all  froru  Locality  Ilk.  Middle  Cambrian  shale,  St.  Francois  County.  Missouri. 
226 


U.  S.   GEOLOGICAL  SURVEY 


MONOGRAPH   LI     PL.LXVII 


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PLATE  LXVII.  227 

ACROTRETA    ARGENTA    Walcott   (j).  674). 

Figures  5,  5',  and  5".  Top,  bark,  and  side  views  of  a  compressed  ventral  valve  in  which  the  foramina!  tube  is  exposed 
by  the  removal  of  the  apex.     U.  S.  Nat.  Mus.  Cat.  No.  52062a. 

5a.  Interior  of  a  ventral  valve.     U.  S.  Nat.  Mus.  Cat.  No.  52062b. 

5b  and  5b'.  Cast  of  a  ventral  valve  that  preserves  the  outline  of  the  visceral  cavity  and  the  trapezoidal 
area  that  includes  the  central,  outside  lateral,  and  middle  lateral  muscle  scars.  It  is  the  type  speci- 
men.    U.  S.  Nat.  Mus.  Cat.  No.  52062c. 

5c.  Partly  exfoliated  dorsal  valve.     U.  S.  Nat.  Mus,  Cat.  No.  52062d. 

5d.  Top  view  of  a  crushed  ventral  valve.  The  dark  portion  preserves  the  shell.  U.  S.  Nat.  Mus.  Cat. 
No.  52062e. 

The  specimens  represented  by  figures  5,  5a-d  are  from  Locality  8b',  Upper  Cambrian  arenaceous  shales,  1  mile 
sotithwest  of  Emigrant  Pass,  Esmeralda  County,  Nevada. 

Figures  5e  and  5e'.  Top  and  side  views  of  a  ventral  valve  from  Locality  7y,  Upper  Cambrian  limestone,  2.5  miles 
southeast  of  Emigrant  Pass,  Esmeralda  County,  Nevada.     U.  S.  Nat.  Mus.  Cat.  No.  35265a. 
5f  and  5g.  Interior  and  cast  of  dorsal  valves  from  Locality  7x,  Upper  Cambrian  limestone,  2.5  miles  south- 
east of  Emigrant  Pass,  Esmeralda  County,  Nevada.     U.  S.  Nat.  Mus.  Cat.  Nos.  35265b  and  35265c, 
respectively. 


PLATE    LXVIII. 


229 


PLATE  LXVIII. 

cl.  Cardinal  scar.  s.  Median  septum  or  ridge. 

fa.  False  area.  v.  Visceral  area, 

fp.  False  pedicle  groove.  vs.  Main  vascular  sinus. 
h.    Central  muscle  scar. 

ACROTRETA    CTTRVATA    Walcott   (p.  682). 

F1GURE8  1,  r.  J";  la,  la',  la";  and  lb,  lb',  lb".  Top,  side,  and  back  views  of  the  exterior  of  ventral  valves.     U.  S. 

Nat.  Mils.  Cat.  Nos.  35269a,  3.5269b,  and  35269c,  respectively.     Figure  la  represents  the  type  specimen. 
Ic,  le',  Ic";  Id,  Id',  Id";  and  le,  le',  le".  Top,  side,  and  back  views  of  casts  of  the  interior  of  ventral 

valves.     U.  S.  Nat.  Mus.  Cat.  Nos.  35269d,  35269e,  and  35269f,  respectively. 
If,  Ig,  Ih,  and  li.  Exterior  and  outline  of  convexity  of  four  dorsal  valves.     U.  S.  Nat.  Mus.  Cat.  Nos.  3o269g, 

35269h,  352691,  and  35269J,  respectively.    The  specimen  represented  by  figiu-e  Ig  was  figiu'ed  by  Walcott 

[1884b,  PI.  I,  fig.  Id]  as  Acrotreta  gemma.     The  specimen  has  been  repeatedly  figured  (see  p.  682). 
Ik  and  11.  Interiors  of  two  dorsal  valves.     U.  S.  Nat.  Mus.  Cat.  Nos.  35269k  and  352691,  respectively.     The 

specimen  represented  by  figure  11  was  figured  by  \Yalcott  [1884b,  PI.  I,  fig.  le]  as  Acrotreta  gemma. 

The  specimen  has  been  repeatedly  figured  (see  p.  682). 
Ira,  Im',  Im",  and  In,  In',  In".  Top,  side,  and  back  views  of  casts  of  the  interior  of  dorsal  valves.     U.  S. 

Nat.  Mus.  Cat.  Nos.  35269m  and  35269n,  respectively. 

The  specimens  represented  are  all  from  Locality  203a,  passage  beds  between  the  Upper  Cambrian  and  the  Ordovi- 
cian,  Hamburg  Ridge,  southwest  of  Wood  Cone,  Eureka  district,  Nevada. 

Acrotreta  idahoensis  Walcott  (]).  687). 

[PI.  LXV,  figs.  1.  la-i] 

Figures  2,  2',  2";  2a,  2a',  2a";  2b,  2b',  2b";  and  2c,  2c',  2c".  Top,  side,  and  back  views  of  four  ventral  valves.     U.  S. 
Nat.  Mus.  Cat.  Nos.  52089a,  52089b,  52089c,  and  52089d,  respectively. 
2d,  2e,  and  2f.  Exterior  and  outline  of  convexity  of  three  dorsal  valves.     U.  S.  Nat.  Mus.  Cat.  Nos.  52089e, 
520891,  and  52089g,  respectively. 

The  specimens  represented  by  figmes  2,  2a-f  are  from  Locality  88a,  Middle  Cambrian  limestone  in  the  northern 
suburbs  of  Deadwood,  Black  Hills,  South  Dakota. 

Figure  2g.  Ventral  valve  from  Locality  165,  Middle  Cambrian  limestone,  about  1  mile  below  the  main  part  of  Dead- 
wood,  Black  Hills,  South  Dakota.     U.  S.  Nat.  Mus.  Cat.  No.  52090a. 

Acrotreta  lisani  Walcott  (p.  692). 

Figures  3^  3a,  and  3b.  Top,  back,  and   side  views  of  a  ventral  valve,  the  type  specimen.     IT.  S.  Nat.  Mus.  Cat. 
No.  52.50.5a. 
3c.  Exterior  of  dorsal  valve.     U.  S.  Nat.  Mua.  Cat.  No.  52505b. 

The  specimens  represented  by  figures  3,  3a-c  are  from   Locality  C22,  Middle  Cambrian,  Changhia  limestone,  at 
Changhia,  Shantung,  China. 

230 


U.  S.   GEOLOGICAL  SURVEY 


MONOGRAPH   Ll     PL.  LXVMI 


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PLATE    LXIX. 


231 


PLATE  LXIX. 

cl.  CardiDal  scar.  s.  Median  septum  or  ridge, 

h.  Central  scar.  vs.  Main  vascular  sinus. 

ACROTRETA    PRIM^VA    Walcott    (p.  700). 

Figures  1,  V,  I";  la,  la',  la";  and  lb,  lb',  lb".  Top,  side,  and  back  views  of  three  ventral  valves.     U.  S.  Xat. 

Mus.  Cat.  No.s.  15343a,  15342a,  and  15342b,   respectively.     The  type  specimen,  represented   by 

figure  1,  was  figirred  by  Walcott  [188(ib,  PL  VIII,  figs.  1  and  la]  as  Acrolrda  gemma.     These  figures 

have  been  repeatedly  copied  (see  p.  700). 
Ic.  Exteriorof  dorsal  valve.     U.  S.  Nat.  Mus.  Cat.  Xo.  15343b.     Specimen  figured  by  Walcott[1886b,  PI.  VIII, 

fig.  lb]  as  Acrolrda  gemma.     This  figure  has  been  repeatedly  copied  (see  p.  700). 
Id.  Cast  of  the  interior  of  a  dorsal  valve.     U.  S.  Xat? Mus.  Cat.  No.  15342c. 
le,  le',  and  le".  Top,  side,  and  back  views  of  a  cast  of  the  interior  of  a  ventral  valve.     U.  S.  Xat.  Mus. 

Cat.  No.  15342d. 
If.  Cast  of  the  interior  of  a  dorsal  valve.     U.  S.  Nat.  Mus.  Cat.  No.  52061a. 

The  specimens  represented  are  all  from  Locality  31a,  Lower  Cambrian  limestone  near  Pioche,  Nevada. 

AcEOTEET,\  PYXiDicuLA  White  (p.  701). 

Figure  2.  Dorsal  valve  from  Locality  313f ,  I^pper  Cambrian  limestone  at  Schellboume,  Nevada.  U.  S.  Nat.  Mus. 
Cat.  No.  8570a.     Specimen  figured  by  White  [1877,  PI.  Ill,  figs.  3a-b(?)]. 

2a  and  2b.  Exterior  and  outline  of  convexity  of  two  dorsal  valves  from  Locality  4h,  Middle  Cambrian  lime- 
stone 4  miles  east-northeast  of  Logan,  Gallatin  Coimty,  Montana.  U.  S.  Nat.  Mus.  Cat.  Nos.  52149a 
and  52149b,  respectively. 

2c,  2c',  2c":  2d,  2d',  2d";  and  2e,  2e'.  2e".  Top.  side,  and  back  views  of  tliree  ventral  valves  associated 
with  the  dorsal  valves  represented  by  figures  2a  and  2b.  U.  S.  Nat.  Mus.  Cat.  Nos.  52149c,  52149d, 
and  52149e,  respectively. 

2f,  2f',  and  2f".  Top,  side,  and  back  views  of  a  ventral  valve  associated  with  the  specimen  represented  by 
figure  2.  U.  S.  Nat.  Mus.  Cat.  No.  8570b.  Type  specimen,  figured  by  White  [1877,  PI.  Ill,  figs.  3c 
and  3d  (?)]. 

3,  3',  and  3".  Top,  side,  and  back  views  of  ventral  valve  from  Locality  6b,  Middle  Cambrian  Langston  lime- 
stone, 2  miles  southea,st  of  Malade,  Oneida  County,  Idaho.     U.  S.  Nat.  Mus.  Cat.  No.  52147a. 

3a,  3a',  and  3a".  Top,  side,  and  back  views  of  cast  of  the  interior  of  a  ventral  valvo  associated  with  the  speci- 
men represented  l)y  figure  3.     V.  S.  Xat.  Mus.  Cat.  Xo.  521471). 

3b.  Top  and  side  views  of  cast  of  the  interior  of  a  dorsal  valve  associated  with  the  specimen  represented  by 
figure  3,  in  which  the  median  ridge  is  slightly  developed.     U.  S.  Nat.  Mus.  Cat.  Xo.  52147c. 

3c  and  3c'.  Top,  side,  and  back  views  of  cast  of  the  interior  of  a  dorsal  valve  as.sociated  with  the  specimen 
represented  by  figure  3,  showing  strong  median  ridge  and  central  and  cardinal  scars.  U.  S.  Nat. 
Mus.  Cat.  No.  52147d. 

3d.  Exterior  and  side  outline  of  convexity  of  a  dorsal  valve  from  Locality  322,  Middle  Camlirian  limestone  15 
miles  west  of  Montpelier,  Idaho.     IT.  S.  Nat.  5Ius.  Cat.  Xo.  52150a. 

3e,  3e',  and  3e".  Top,  side,  and  back  views  of  a  cast  of  the  interior  of  a  ventral  valve  associated  with  the 
specimen  represented  liy  figme  3.     U.  S.  Nat.  Mus.  Cat.  Xo.  52147e. 

3f,  3f',  and  3f".  Top,  side,  and  back  views  of  the  interior  of  a  ventral  valve  associated  with  the  specimen 
represented  by  figiu-e  3d.    If.  S.  Nat.  Mus.  Cat.  Xo.  52150b. 

AcROTRETA    SIGNALI.S    Walcotl    (p.  711). 

Figures  4,  4',  and  4".     Top,  side,  and  back  ■\'iews  of  a  ventral  valve,  the  type  specimen,  from  Locality  328e,  Middle 
Cambrian  sandstone  at  St.  Croix  Falls,  Polk  County,  Wisconsin.     The  foraminal  aperture  of  4"  is 
restored  from  a  second  specimen.     U.  S.  Xat.  Mus.  Cat.  Xo.  35285a. 
232 


U.   S.   GEOLOGICAL   SURVEY 


MONOGRAPH   LI     PL.   LXIX 


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FRANCES  WIESER  DEL. 


PLATE  LXIX.  233 

ACROTRETA    SHANTUNGENSIS    Walcott  (p.  710). 

Figures  5,  5a,  and  5b.  Top,  side,  and  hark  \-iews  of  a  ventral  valve,  the  type  specimen.     U.  S.  Nat.  Mus.  Cat. 
No.  52512a. 
5c.  Top  view  of  a  ventral  valve  with  the  apex  broken  off.     IT.  S.  Nat.  Mus.  Cat.  No.  52512b. 
5d.  Exterior  of  a  dorsal  valve.     U.  S.  Nat.  Mus.  Cat.  No.  52512c. 
5e.  Interior  of  a  dorsal  valve.     U.  S.  Nat.  Mus.  Cat.  No.  52512d. 

The  specimens  represented  are  all  from  Locality  C62,  Middle  Cambrian  limestone  2.5  miles  south  of  Yenchuang, 
Sintai  district,  Shantung,  China. 

AcROTRETA  PACiFicA  Walcott  (p.  699). 

Fksures  6  and  6a.  Top  and  side  views  of  an  elevated  ventral  valve,  the  type  specimen,  from  Locality  C5,  Middle 
Cambrian  limestone  3.2  miles  southwest  of  Yenchuang,  Sintai  district,  Shantung,  China.  U.  S.  Nat. 
Mus.  Cat.  No.  52506a. 

6b,  6c,  and  6d.  Top,  back,  and  side  views  of  a  ventral  valve  with  pointed  apex,  associated  with  the  specimen 
represented  by  figures  6  and  6a.     U.  S.  Nat.  Mus.  Cat.  No.  52506b. 

6e.  Partly  exfoliated  dorsal  valve  from  Locality  C2,  Middle  Cambrian  limestone  2  miles  south  of  Yen- 
chuang, Sintai  district,  Shantung,  China.     U.  S.  Nat.  Mus.  Cat.  No.  52508a. 


PLATE    LXX. 


235 


PLATE  LXX. 

cl.  Cardinal  scar.  vs.  Main  vascular  slnns. 

h.  Central  scar.  x.  Cast  of  foraininal  aperture, 

s.  Median  septum  or  ridge. 

ACROTBETA    SCHMALENSEEI  Walcott  (p.  709). 

FiGDRE,s  1,   1',  and  1".  Top,  back,  and  side  views  of  ventral  valve.     U.  S.  -Nat.  Mus.  Oat.  No.  182031. 

J  a,  la',  la";  lb,  lb',  lb";  Ic,  Ic',  Ic";  and  Id,  Id',  Id".  Top,  side,  and  back  views  of  typical  forms  of  the 

ventral  valve.     U.  S.  Nat.  Mus.  Cat.  Nos.  18203a-d,  respectively.     Figure  la  represents  the  type 

specimen, 
le,  le',  le";  If,  If,  If";  Ig,  Ig',  Ig";  Ih,  Ih',  Ih";  and  li,  li',  li".  Top,  side,  and  back  views  of  casts  of  the 

interior  of  ventral  valves.     U.  S.  Nat.  Mus.  Cat.  Nos.  lS203e-i,  respectively. 
lj>  Ij',  W;  Ik,  Ik',  Ik";  11,  11',  11";  Im,  Im',  Im";  In,  In',  In";  and  lo,  lo',  lo".  Top,  side,  and  back 

views  of  casts  of  the  interior  of  dorsal  valves.     U.  S.  Nat.  Mus.  Cat.  Nos.  18203j-o,  respectively. 
Ip.  Cast  of  the  interior  of  a  dorsal  valve  with  a  small  and  short  median  ridge.     U.  S.  Nat.  Mus.  Cat.  No. 

18203p. 
Iq  and  Ir.  Exteriors  and  side  outlines  of  two  dorsal  valves.     U.  S.  Nat.  Mus.  Cat.  Nos.  18203q  and  18203r, 

respectively. 
Is,  Is',  and  Is".  Top,  back,  and  side  views  of  the  cast  of  a  ventral  valve  in  which  the  ijiterior  vascular  mark- 
ings are  unusually  faint  for  this  species.     U.  S.  Nat.  Mus.  Cat.  No.  18203s. 

The  specimens  represented  by  figures  1,  la-s  are  from  Locality  8w,  Middle  ('ambrian  limestone  of  the  Faradoxides 
forchhammcri  zone  at  Andrarum,  Province  of  Christ ianstad,  Sweden. 

ACROTRETA  EGGEGRUNDENSIS  Wimail  (p.  684). 

Figures  2a,  2b,  and  2c.  Top,  side,  and  back  views  of  a  ventral  vahe  from  Locali)>  311,  Middle?  Cambrian  sandstone 
bowlder  No.  3,  on  Eggegrund  Island,  Gefle  Bay,  Sweden.  Type  specimen  in  the  collection  of  the 
University  of  Upsala;  cast  iu  the  United  States  National  Museum  (Cat.  No.  .57099a).  Specimen 
figured  in  corresponding  positions  by  Wmian  [1902,  PI.  II,  figs.  29,  27,  and  20,  respectively]. 
2d.  Dorsal  valve  associated  with  the  ventral  valve  represented  by  figiu-es  2a-c.  Original  in  the  collection  of 
the  University  of  Upsala;  cast  in  the  United  States  National  Museum  (Cat.  No.  •57099b).  Specimen 
figured  by  Wiman  [1902,  PI.  II,  fig.  24]. 

AcROTRETA  uPLANDicA  Wimao  (p.  714). 

Figures  3,  3a   and  3b.  Top,  side,  and  back  views  of  the  type  specimen,  a  ventral  valve,  from  Locality  311b.  Middle? 
Cambrian  sandstone  bowlder  No.  2  on   liiludden,   near  Getle,  Sweden.     Original  in  the  collection 
of  the  Univer.sity  of  Upsala;  cast  in  the  United  States  National  Museum  (Cat.  No.  .57100a). 
3c.  Dorsal  valve  associated  with  the  specimen  represented  by  figures  3,  3a-b.     Original  in  the  collection  of 
the  University  of  Upsala;  cast  in  the  United  States  National  ^Museum  (Cat.  No.  .57100b). 

Figures  3,  3a-c  are  redrawn  from  the  specimens  figureil  by  'Wiman  [1902,  PI.  II,  figs.  15-18,  respectively], 

ACROTRETA    I'PLAXDICA    LlMOENSl.S   (Williail)   (p.  714). 

Figures  4,  4a,  and  4b.  Top,  side,  and  back  views  of  the  tyi>e  specimen,  a  ventral  valve,  from  Locality  311n,  Middle  ? 
Cambrian  sandstone  bowlder  No.  fi  on  Limon  Island,  Getle  Bay,  Sweden,     Original  in  the  collection 
of  the  University  of  Upsala;  cast  in  the  United  States  National  Museum  (Cat,  No,  57101a), 
4c.  Dorsal  valve  associated  with  the  specimen  represented  by  figm-es  4,  4a-b.     Original  in  the  collection  of 
the  University  of  Upsala;  cast  in  the  United  States  National  Museum  (Cat.  No.  57101b). 

Figures  4,  4a-c  are  redrawn  from  the  specimens  figured  by  Wiman  [1902.  PI.  II,  figs.  19-22]  as  Acrotreta  limoensis. 

236 


U.  S.   GEOLOGICAL  SURVEY 


MONOGRAPH  LI     PL.  LXX 


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MELIOTVPE    CO    BOSTOU 


PLATE   LXXI. 


237 


PLATE  LXXI. 

cl.  Cardinal  scar.  v.  Visceral  area. 

fa.  Fal-se  area.  vs.  Main  vascular  sinus. 

h.  Central  scar.  .\'.  Cast  of  foramin;il  aperture. 

s.  Median  septum.  x".  Cast  of  apicalcallosity. 

ACROTRETA    SAGITTALIS    TACONICA    (Walcott)    (p.  707). 

Figures  1,  1',  and  1".  Toj),  sido,  and  back  views  of  a  ventral  valvo  from  Locality  37b,  Lower  Cambrian  limestone  east 

of  Salem,  Washington  County,  New  York.     U.  S.  Nat.  Mus.  Cat.  No.  .52161a. 
la,  la',  and  la".  Interior  of  ventral  valve  associated  with  the  specimen  represented  by  figure  1.     IT.  S.  Nat. 

Mus.  Cat.  No.  521Glb. 
lb,  lb',  lb",  and  Ic,  Ic',  Ic".  Top,  back,  and  side  views  of  casts  of  the  interior  of  ventral  valves  from  Locality 

38a,  Lower  Cambrian  limestone  south  of  North  Granville,  Washington  County,  New  York.     U.  S. 

Nat.  Mus.  Cat.  Nos.  52163a  and  52163b,  respective]  v.     The  type  specimen,  represented  by  figure  Ic, 

was  figured  by  Walcott  [1887,  PL  I,  fig.  18b]. 
Id,  Id',  and  Id".  Interior  of  a  ventral  valve  from  Locality  44a,  Lower  Cambrian  limestone  on  Valatie  Kill, 

Rensselaer  County,  New  York.     U.  S.  Nat.  Mus.  Cat.  No.  52165a. 
le,  le',  and  le".  Interior  of  a  ventral  valve  associated  with  the  specimen  represented  by  figure  1.     I".  S. 

Nat.  MuB.  Cat.  No.  52161c. 
If.  Dorsal  j/alve  from  Locality  361),  Lower  Cambrian  limestone  near  Greenwich,  Washington  County,  New 

York.     U.  S.  Nat.  Mus.  Cat.  No.  52166a. 
Ig.  Exterior  and  outline  of  convexity  of  dorsal  valve  from  Locality  22,  Lower  Cambrian  limestone  near  North 

Granville,  Washington  County,  New  York.     U.  S.  Nat.  Mus.  Cat.  No.  52164a. 
Ih.  Exterior  and  outline  of  convexity  of  dorsal  valve  from  Locality  36,  Lower  Cambrian  limestone  south  of 

Shushan,  Washington  County,  New  York.     U.  S.  Nat.  Mus.  Cat.  No.  17441a.     Specimen  figured  by 

Walcott  [1887,  PL  I,  fig.  18c]. 
li  and  Ij.  Casts  of  the  interior  and  outline  of  convexity  of  dorsal  valves  associated  with  the  specimen  repre- 
sented by  figure  1.     U.  S.  Nat.  Mus.  Cat.  Nos.  52161d  and  52161e,  respectively. 
Ik.  Interior  of  a  dorsal  valve  associated  wnth  the  specimen  represented  by  figure  1.     V.  S.  Nat.  Mus.  Cat. 

No.  52161f. 
11,  11',  and  Im,  Im'.  Casts  of  the  interior,  with  back  \-iew  and  outline  of  convexity,  of  two  dorsal  valves 

associated  with  the  specimen  represented  by  figure  1.     V .  S.  Nat.  Mus.  Cat.  Nos.  52161g  and  52161h, 

respectively. 
In.  Cast  of  the  interior  and  outline  of  convexity  of  dorsal  \-al\e  associated  with  tlie  specimen  represented 

by  figure  1.    U.  S.  Nat.  Mus.  Cat.  No.  521611. 
lo.  Interior  of  a  ventral  valve  from  Locality  34,  Lower  Cambrian  limestone  at  Low  Hampton,  Washington 

County,  New  York,  showing  the  apical  callosity  and  fine  grooves  radiating  forward  from  it.     U.  S. 

Nat.  Mus.  Cat.  No.  52162b.     Another  specimen  (Cat.  No.  62163c,  Locality  38a)  was  used  to  restore 

certain  portions  of  this  figure.     Specimen  figured  by  Walcott  [1887,  PI.  I,  fig.  18a]. 

AcROTRETA  SAGITTALIS   (Salter)  (p.  704). 

Figures  2,  2',  2";  2a,  2a',  2a";  2b,  2b',  2b";  and  2c,  2c',  2c".  Top,  .side,  and  back  views  of  casts  of  the  interior  of  four 
ventral  valves  from  Locality  8w,  Middle  Cambrian  limestones  at  Andrarum,  Province  of  Christ ianstad, 
Sweden.     U.  S.  Nat.  Mus.  Cat.  Nos.  52156a,  52156b,  52156c,  and  52156d,  respectively. 

2d,  2d',  and  2f,  2f'.  Top  and  back  views  of  two  dorsal  valves  from  Locality  6i,  Middle  Cambrian  limestone 
near  Fosters  Point,  Random  Sound,  Newfoundland.  U.  S.  Nat.  Mus.  Cat.  Nos.  521.52a  and  52152b, 
respectively. 

2e  and  2e'.  Top  and  back  views  of  dorsal  valve  from  Locality  2s,  Middle  Cambrian  limestones  at  Hastings  Cove, 
Kennebecasis  Bay,  St.  John  County,  New  Brunswick,     Museum?. 

2g.  Back  view  of  ventral  valve.  From  Borregaard,  Bornholm,  Denmark  (horizon  unknown).  Copenhagen 
LTniversity  Museum. 

2h.  Back  view  of  cast  of  dorsal  valve.  From  Borregaard,  Bornholm,  I>enmark  (horizon  unknown).  Copen- 
hagen University  Museum. 

3,  3',  3",  and  3a,  3a',  3a".  Top,  back,  and  side  views  of  casta  of  the  interior  of  ventral  valves  from  Locality 
318g,  Middle  Cambrian  shales  near  St.  Da\-id8,  South  Wales.  U.  S.  Nat.  Mus.  Cat.  Nos.  52155a  and 
52155b,  respectively. 

3b,  3c,  3d,  and  3e.  Ventral,  side,  back,  and  dorsal  views  of  a  cast  of  the  two  valves  united  from  Locality  8w, 
Middle  Cambrian  limestones  at  Andrarum,  Sweden.     U.  S.  Nat.  Mus.  Cat.  No.  52156e. 

3f.  Cast  of  a  ventral  valve  with  truncated  apex,  associated  with  the  specimen  represented  by  figure  3.  V .  S. 
Nat.  Mus.  Cat.  No.  52155c. 

3g,  3g',  3g",  and  3h,  3i,  and  3j.  Casts  of  the  interior  of  four  dorsal  valves,  with  outlines  of  convexity.     Asso- 
ciated with  the  specimen  represented  by  figure  3.    U.  S.  Nat.  Mus.  Cat.  Nob.  52155d,  52155e,  52155f, 
and  521.55g,  respectively. 
238 


U.  S.   GEOLOGICAL  SURVEY 


MONOGRAPH   LI     PL.   LXXI 


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FRANCES  WIESER  DEL. 


MELIOTVee    CO   BOSTOM 


PLATE    LXXII. 


239 


PLATE  LXXII. 

cl.  Cardinal  soar.  v.  Visceral  area. 

fa.  False  area.  vs.  Main  vascular  sinus. 

h.  Central  scar.  x'.  Cast  of  foraminal  aperture. 

s.  Median  septum  or  ridge.  x".  Cast  of  apical  callosity. 

ACROTKETA    SAGITTALIS    TRANSVERSA   (TIartt)    (p.   708). 

Figures  1,  1',  1";  la,  la',  la";  and  lb.  Top,  side,  and  back  views  of  casts  of  interior  of  three  ventral  valves.     U.  S. 

Nat.  Mus.  Cat.  Nos.  52160a,  52160b,  and  52160c,  respectively. 
Ic.  A  ventral  valve  with  a  portion  of  the  outer  shell.     U.  S.  Nat.  Mus.  Cat.  No.  52160d. 
Id  and  Id'.  Cast  of  the  interior  of  dorsal  valve,  with  side  view.     U.  S.  Nat.  Mus.  Cat.  No.  52160e. 
le.  le',  le";  If,  If,  If";  and  Ig,  Ig'.  Ig".     Top,  back,  and  side  views  of  casts  of  interior  of  dorsal  valves. 

U.  S.  Nat.  Mus.  Cat.  Nos.  52160f.  52160g,  and  52160h.  respectively. 
Ih,  11,  and  Ij.  Side,  dorsal,  and  back  views  of  a  cast  of  the  two  valves.     U.  S.  Nat.  Mus.  Cat.  No.  521601. 
Ik.  Interior  of  a  dorsal  valve  pressed  down  on  a  ventral  valve.     U.  S.  Nat.  Mus.  Cat.  No.  52160J. 

The  specimens  represented  are  all  from  Locality  3,  Upper  Cambrian  .^haly  limestone  300  feet  (91.4  m. )  above  the 
Pwadorides  zone,  Manuels  Brook,  Conception  Bay.  Newfoundland. 

ACROTRETA  .  MISERA   (Billillgs)    (p.   695). 

Figures  2,  2'.  and  2".  Top.  side,  and  back  \-iews  of  cast  of  ventral  valve.     U.  S.  Nat.  Mus.  Cat.  No.  52128m. 

2a,  2a',  2a";  2b,  2b',  2b";  2c,  2c',  2c";  and  2d,  2d',  2d".  Top,  side,  and  back  -^iews  of  casts  of  ventral 

valves.     U.  S.  Nat.  Mus.  Cat.  Nos.  52128a-d,  respectively. 
2e.  2e'.  and  2e".  Top.  side,  and  back  views  of  exterior  of  ventral  valve.     U.  S.  Nat.  Mus.  Cat.  No.  52128e. 
2f  and  2g.  Exterior  and  outline  of  convexity  of  two  dorsal  valves.     U.  S.  Nat.  Mus.  Cat.  Nos.  52128f  and 

52128g,  respectively. 
2h.  Interior  of  dorsal  valve.     U.  S.  Nat.  Mus.  Cat.  No.  52128h. 
2i,  21',  21";  2j,  2j',  2j";  2k,  2k'.  2k";  and  21,  21',  21".    Top,  side,  and  back  views  of  casts  of  the  interior  of 

dorsal  valves.     U.  S.  Nat.  Mus.  Cat.  Nos.  521281-1,  respectively. 

The  specimens  represented  are  all  from  Locality  1,  Middle  Cambrian,  shales  of  zone  A  of  No.  7  of  the  Manuela 
Brook  section  [Walcott,  1891b,  p.  261],  Manuels  Brook,  Conception  Bay,  Newfoimdland. 
240 


U.  S.  GEOLOGICAL  SURVEY 


MONOGRAPH  LI     PL.  LXXII 


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FRANCES  WIE3ER  DEL. 


MELIOTVPE    CO  BCSrOM 


PLATE    LXXIII. 


62667°— VOL  51,  pt  2—12 16  241 


PLATE  LXXIII. 

cl.  Cardinal  scar.  s.  Median  septum, 

fa.  False  area.  vs.  Main  vascular  sinus, 

fp.  False  pedicle  groove.  x'.  Cast  orforaminal  aperture, 

h.  Central  scar.  Jt".  Cast  of  apical  callosity. 

AcEOTKETA  NiCHOLSONi  Davidsoii  (p.  696). 

[PI.  LXXIII,  figs.  6,  Ga-b.] 

FiGlTRE  1.  Top  and  side  views  of  a  compressed  ventral  valve,  the  type  specimen.     Copied  from  Davidson  [1868,  PL 
XVI,  fig.  14]. 
la  and  lb.  Compressed  ventral  valves.     Copied  from  Davidson  [1871,  PI.  XLIX,  figs.  38  and  39,  respectively]. 
Ic.  Exterior  of  dorsal  valve.     Copied  from  Davidson  [1868,  PI.  XVI,  fig.  15]. 
Id.  Interior  of  dorsal  valve.     Copied  from  Davddson  [1868,  PI.  XVI,  fig.  16]. 

The  specimens  represented  by  figm-es  1,  la-d  are  from  Locality  316,  Lower  Ordovician,  Upper  Lkndeilo?  "Black 
shales"  at  Dobbs  Linn,  near  Moffat,  in  Dumfriesshire,  Scotland. 

Figures  le.  It,  and  Ig.  Front,  side,  and  back  views  of  ventral  valve,  from  Locality  316a,  Lower  Ordovician,  Llandeilo, 

at  Craighead,  Girvan  district,  AjTshire,  Scotland. 
Ih  and  li.  Back  and  front  views  of  a  ventral  valve,  from  Locality  316a,  Lower  Ordovician,  Llandeilo,  at 

Balcletchie,  Girvan  district,  Ayrshire,  Scotland. 
Ij.  Exterior  of  the  dorsal  valve  attached  to  the  specimen  represented  by  figtu-es  le.  If,  and  Ig. 
Ik.  Exterior  of  the  dorsal  valve  attached  to  the  specimen  represented  by  figiu-es  Ih  and  li. 

Figures  le-k  are  copied  from  Davidson  [1883,  PL  XVI,  figs.  21a,  21c,  21b,  22a.  22b,  21d,  and  22c,  respectively]. 
AcROTRETA  suBCOXicA  Kutorga  (p.  713). 

Figures  2,  2a-d.  Ventral  and  dorsal  valves.  Copied  from  Kutorga  [1848,  PI.  VII,  figs.  7a,  7b,  7c,  7b',  and  7c',  respec- 
tively]. The  specimens  represented  by  figures  2,  2c,  and  2d  are  redrawn  in  figures  2e,  2h,  and  2i, 
respectively,  of  this  plate. 

2e.  Ventral  valve.     Specimen  figured  by  Kutorga  [1848,  PI.  VII,  fig.  7a].     (See  fig.  2.) 

2f  and  2g.  Side  and  posterior  views  of  the  type  specimen  in  Kutorga's  collection  preserving  both  ventral 
and  dorsal  valves.  The  dorsal  valve  shown  in  these  figures  is  the  one  figured  by  Kutorga  [1848, 
PL  VII,  fig.  7c'].     A  top  view  of  it  is  given  in  figure  2i. 

2h.  Posterior  view  of  a  ventral  valve  showing  the  median  groove  and  pedicle  aperture.  Specimen  figured 
by  Kutorga  [1848,  PI.  VII,  fig.  7b'].     (See  fig.  2c.) 

2i.  Dorsal  valve  shown  in  side  outliae  by  figures  2f  and  2g.  Specimen  figured  by  Kutorga  [1848,  PI.  ^'II, 
fig.  7c'].    (See  fig.  2d.) 

The  specimens  represented  are  from  Locality  336,  ( )rdovi(ian,  Echinosphaeriles  limestone,  horizon  Cla,  at  Popowka, 
near  St.  Petersburg,  Russia. 

AcEOTRETA  sociALis  voii  Seebacli  (]i.  711). 

Figures  3  and  3a.  Side  and  back  views  of  ventral  valve,  the  type  specimen. 
3b.  Interior  of  ventral  valve. 
3c.  Cast  of  dorsal  valve. 

The  specimens  represented  by  figures  3,  3a-c  are  from  Locality  334g,  Middle  Cambrian,  Bornholm  Island,  Den- 
mark.    The  figures  are  copied  from  von  Seebach  [1865,  PL  Villa,  figs.  1-4,  respectively]. 

Figures  4  4',  A",  and  4a,  4a',  4a".  Top,  back,  and  side  views  of  two  ventral  valves  from  Locality  8z.  Middle  Cambrian 
limestones  of  the  Paradox-ides  alatidicus  zone  at  Borgholm,  Oeland  Island,  Sweden.  IT.  g.  Nat. 
Mus.  Cat.  Nos.  35286a  and  3528Kb,  respectively. 
4b,  4b',  and  4b".  Top,  back,  and  side  views  of  a  cast  of  part  of  the  interior  of  a  ventral  valve  from  Locality 
8w,  Middle  Cambrian  limestones  of  the  ParadoxidfS  forchhammeri  zone  at  Andrarum,  20  miles  (32  km.) 
northwest  of  Simrishanin,  Province  of  Chrislianstad,  Sweden.  U.  S.  Xat.  Mus.  Cat.  Xo.  52174a. 
242 


U.  S.   GEOLOGICAL  SURVEY 


MONOGRAPH   LI     PL.  LXXIII 


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PLATE  LXXIII.  243 

AcROTRETA  sociALis  voii  Seebach — Continued. 

Figures  4c,  4c',  4c",  and  4c'".  Top,  back,  side,  and  front  views  of  a  cast  of  the  interior  of  a  ventral  valve,  showing 

very  strong  cardinal  scars  and  main  vascular  sinuses,  associated  with  the  shells  represented  by  figures 

4  and  4a.     U.  S.  Nat.  Mus.  Cat.  No.  35286c. 
4d.  Exterior  and  side  views  of  a  dor.sal  valve  associated  with  the  shells  represented  by  figures  4  and  4a.     U.  S. 

Nat.  Mus.  Cat.  No.  35286d. 
4e.  Cast  of  the  interior  of  dorsal  valve  associated  with  the  shells  represented  by  figures  4  and  4a.     U.  S.  Nat. 

Mus.  Cat.  No.  3528(ie. 

AcROTRETA  SABRING   (Callaway)  (p.  702). 

Figures  5,  5',  and  5".  Top,  side,  and  back  views  of  a  cast  of  part  of  the  interior  of  a  ventral  valve.     U.  S.  Nat.  Mus. 

Cat.  No.  57102a. 
5a,  5a',  and  5a".     Top,  side,  and  back  views  of  a  partly  compressed  ventral  valve.     U.  S.  Nat.  Mus.  Cat. 

No.  57102b. 
5b.  Cast  of  the  interior  of  a  dorsal  valve.     Type  specimen,  figured  by  Callaway  [1877,  PL  XXIV,  fig.  12]  ae 

Obolella  sabrina;.     Collection  of  Dr.  Charles  Lapworth. 
5c.  Exterior  of  a  dorsal  valve.     U.  S.  Nat.  Mus.  Cat.  No.  57102c. 
5d.  Cast  of  the  interior  of  a  dorsal  valve.     U.  S.  Nat.  Mus.  Cat.  No.  57102d. 

The  specimens  represented  are  all  from  Locality  304h,  Upper?  Cambrian  Shineton  shales,  Mary  Dingle,  South 
Shropshire,  England. 

AcROTRETA  NICH0L80NI  Davidson  (p.  696). 

[PI.  LXXIII,  flgs.  1,  la-k.] 

Figures  6,  6a,  and  6b.  Top,  side,  and  back  views  of  cast  of  ventral  valve  from  Locality  304h,  Upper  ?  ( 'ambrian  Shine- 
ton  shales,  Mary  Dingle,  South  Shropshire,  England.     U.  S.  Nat.  Mus.  Oat.  No.  52131a. 


PLATE   LXXIV. 


245 


PLATE  LXXIV. 

a.  Area.  v.  Visceral  area, 

cl.  Cardinal  scar.  vs.  Main  vascular  sinus, 

h.  Central  scar.  ^"-  Cast  of  apical  callosity, 
s.  Median  septum. 

ACROTRETA    OPHIRENSIS    Walcott  (p.  697). 

Figures  1,  1',  and  1".  Top,  side,  and  back  viow.s  of  ventral  valve,  the  type  specimen.     U.  S.  Nat.  Mus.  Cat.  No. 

35281q. 
la,  la',  la";  lb,  lb',  lb";  and  Ic,  Ic',  Ic".  Top,  side,  and  back  views  of  ventral  valves  that  illustrate 

variation  in  form.     U.  S.  Nat.  Mus.  Cat.  Nos.  36281a-c,  re.spectively. 
Id,  Id',  and  Id".  Top,  back,  and  side  views  of  cast  of  interior  of  a  ventral  valve.     U.  S.  Nat.  Mus.  Cat.  No. 

35281d. 
le.  Cast  of  the  interior  of  a  ventral  valve,  showing  outlines  of  visceral  cavity.     U.  S.  Nat.  Mus.  Cat.  No. 

35281e. 
If.  Interior  of  ventral  valve  with  area  preserved.     U.  S.  Nat.  Mus.  Cat.  No.  35281f. 
Ig.  Cast  of  interior  of  a  dorsal  valve.     U.  S.  Nat.  Mus.  Cat.  No.  35281g. 

Ih.  Cast  of  part  of  the  interior  of  a  dorsal  valve  broadened  by  distortion.     U.  S.  Nat.  Mus.  Cat.  No.  35281h. 
li.  Cast  of  the  interior  of  a  dorsal  valve  narrowed  by  distortion.     U.  S.  Nat.  Mus.  Cat.  No.  352811. 
Ij,  Ij',  and  Ij".  Top,  side,  and  back  views  of  exterior  of  dorsal  valve.     U.  S.  Nat.  Mus.  Cat.  No.  35281J. 
Ik  and  Ik'.  Top  and  side  views  of  a  dorsal  valve.     U.  S.  Nat.  Mus.  Cat.  No.  3o281k. 
1 1.  Interior  of  a  dorsal  valve.     U.  S.  Nat,  Mus.  Cat.  No.  352811. 
Im,  Im',  Im",  and  In,  In',  In".  Top,  side,  and  back  views  of  casts  of  interior  of  elongated  dorsal  valves. 

U.  S.  Nat.  Mus.  Cat.  Nos.  35281m  and  35281n,  respectively, 
lo.  Interior  of  a  finely  preserved  dorsal  valve.     U.  S.  Nat.  Mus.  Cat.  No.  35281o. 
Ip.  Cast  of  the  interior  of  an  undistorted  dorsal  valve.     U.  S.  Nat.  Mus.  Cat.  No.  .3.5281p. 

The  specimens  represented  are  all  from  Locality  3e,  Middle  Cambrian  limestone  less  than  400  feet  (121.9  m.)above 
the  quartzitic  sandstones,  at  Ophir,  Oquirrh  Range,  Tooele  County,  Utah. 

AcROTRETA    OPHIRENSIS    RUGOSA    Walcott   (p.  699). 

Figure  2.  Interior  of  a  ventral  valve.     U.  S.  Nat.  Mus.  Cat.  No.  35282a. 

2a  and  2a'.  Top  and  side  views  of  a  ventral  valve,  the  type  specimen.     U.  S.  Nat.  Mus.  Cat.  No.  35282b. 

2b  and  2b'.  Top  and  side  views  of  a  cast  of  the  interior  of  a  ventral  valve.     U.  S.  Nat.  Mus.  Cat.  No.  35282c. 

2c  and  2c'.  Top  and  side  views  of  a  dorsal  valve.     U.  S.  Nat.  Mus.  Cat.  No.  35282d. 

2d.  Interior  of  a  dor.sal  valve.     U.  S.  Nat.  Mus.  Cat.  No.  35282e. 

2e.  Cast  of  interior  of  a  dorsal  valve.     U.  S.  Nat.  Mus.  Cat.  No.  35282f. 

The  specimens  represented  are  all  from  Locality  3e,  Middle  Cambrian  limestone  less  than  400  feet(121.9  m.)  above 
the  quartzitic  sandstones,  at  Ophir,  Oquirrh  Range,  Tooele  County,  Utah. 

AcROTRETA    CLAYTONI    Walcott   (p.  680). 

Figures  3,  3',  and  3".  Top,  side,  and  back  views  of  a  ventral  valve  from  Locality  175,  Lower  Cambrian  shales  on  the 
divide  between  Clayton  and  Fish  Lake  valleys,  about  15  miles  (24.2  km.)  south-southwest  of  the  town 
of  Silver  Peak,  Silver  Peak  quadrangle  (U.  S.  Geol.  Survey),  E.smeralda  County,  Nevada.  U.  S.  Nat. 
Mus.  Cat.  No.  52080a.    This  is  the  type  specimen. 

3a.  Partly  exfoliated  dor.sal  valve  ai^-sociated  with  the  specimen  represented  by  figure  3.     U.  S.  Nat.  Mua. 
Cat.  No.  52080b. 

3b.  Cast  of  interior  of  a  distorted  ventral  valve  from  Localily  11,  Lower  Cambrian  limestones  of  No.  3  of  the 
Silver  Peak  group  [Walcott,  1908f,  p.  189],  about  2.5  miles  (4  km.)  south  of  Barrel  Spring,  and  0.5 
mile  (0.8  km.)  east  of  the  road,  in  the  extreme  southeastern  corner  of  the  Silver  Peak  (juadrangle 
(U.  S.  Geol.  Survey),  Esmeralda  County,  Nevada.     U.  S.  Nat.  Mus.  Cat.  No.  52081a. 
246 


U.  S.   GEOLOGICAL  SURVEY 


MONOGRAPH   LI     PL.  LXXIV 


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FRANCES  W1E8EH  DEL. 


MCLIOTVPE    CO    BOSTOM 


PLATE    LXXV. 


247 


PLATE  LXXV. 

AcROTKETA  RUDis  Walcott  (p.  702). 

[PI.  LXV.flg.  3f.] 

Figure  1.  Enlargement  by  photography  of  a  small  piece  of  arenaceous  shale  on  which  the  casts  of  three  ventral  and 
three  dorsal  valves  have  lieen  compressed.  The  ventral  valves  are  crushed  and  spread  out  toward 
the  aperture.  Locality  121,  Middle  Cambrian  Rogersville  shale,  road  just  east  of  Harlan  Knob, 
4  miles  (G.4  km.)  northeast  of  Rogersville  [Keith,  1905,  areal  geology  sheet],  Hawkins  County,  Ten- 
nessee.    U.  S.  Nat.  Mus.  Cat.  No.  52112a. 

ACROTRETA    CONULA    Walcott  (p.  6S1). 

FiGUKE  2.  Enlargement  by  photography  of  a  fragment  of  shale  studded  with  shells  of  this  species.  Locality  310a, 
Upper  Cambrian  shales  of  Olcnus  truncatus  zone,  on  Oeland  Island.  Sweden.  U.  S.  Nat.  Mus.  Cat. 
No.  35267a. 

2a.  Cast  of  interior  of  a  dorsal  valve.     U.  S.  Nat.  Mus.  Cat.  No.  35267a. 

2b.  A  vertically  compressed  ventral  valve,  the  type  specimen.     U.  S.  Nat.  Mus.  Cat.  No.  35267a. 

Figure  2a  is  drawn  from  the  specimen  which  is  partly  cut  by  the  lower  margin  of  figure  2,  just  to  the  left  of  the 
center.     Figure  2b  is  of  a  specimen  from  the  same  slab  of  shale  but  outside  the  limits  of  figure  2. 

AcROTHYRA  PROAViA   (Mattliew)  (p.  717). 

[PI.  LXXVI,  figs.  3,  3a-u.] 

FiGCEE  3.  Enlargement  by  photography  of  a  small  piece  of  limestone  in  which  numerous  ventral  and  dorsal  valves 
are  embedded.     The  varying  shape  of  the  ventral  valves  is  well  illustrated.     Locality  lOq,  Middle 
Cambrian  sandstone  below  the  waterfall  in  Division  E2b  of  Matthew's  [1903,  p.  21]  Etcheminian, 
Dugald  Brook,  Indian  River,  eastern  Cape  Breton,  Nova  Scotia.     U.  S.  Nat.  Mus.  Cat.  No.  52052r. 
248 


U.  S.   GEOLOGICAL  SURVEY 


MONOGRAPH   LI     PL.  LXXV 


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249 


PLATE  LXXVI. 

cl.  Cardinal  scar.  vs.  Main  vascular  sinus. 

Ip.  False  pedicle  groove.  x.  Foraminal  aperture. 

s.  Median  septum  or  ridge.  x'.  Cast  of  foraminal  tube. 

V.  Visceral  area.  x".  Cast  of  apical  callosity. 

AcROTRETA  i.NfFLATA   (Matthew)   (p.  690). 

FiGUEES  1  and  V.  Top  and  side  views  of  an  unu.sually  well-preserved  ventral  valve,  showing  radiating  lines  on 

inner  lamellse  of  the  shell.     Locality  2f,  Middle  Cambrian  sandstones  of  Division  Ibl  of  Matthew's 

[1895,  p.  108]  Protolenus  zone,  Hanford  Brook,  St.  John  County,  New  Brunswick.     U.  S.  Nat.  Mus. 

Cat.  No.  3.5276a. 
la  and  la'.  Top  and  side  views  of  an  elevated  ventral  valve  associated  with  the  specimen  represented  by 

figure  1.     U.  S.  Nat.  Mus.  Cat.  No.  3527Gb. 
lb  and  lb'.  Top  and  side  \'iews  of  a  ventral  valve  associated  with  the  specimen  represented  by  figure  1, 

with  the  apex  broken  off  so  as  to  show  the  cast  of  the  large  apical  callosity  and  the  base  of  the  small 

foraminal  tube.     U.  S.  Nat.  Mus.  Cat.  No.  35276c. 
Ic,  Ic',  and  Ic".  Top,  side,  and   back  views  of  a   partly  exfoliated   ventral   valve  associated  with   the 

specimen  represented  by  figure  1,  showing  cast  of  the  large  cardinal  muscle  scars  and  apical  callosity. 

U.  S.  Nat.  Mus.  Cat.  No.  35276d. 
Id  and  Id'.  Top  and  side  views  of  a  ventral  valve  in  which  the  false  area  slopes  forward.     Middle  Cam- 
brian sandstones  of  Di^'ision  Ibl  (the  general  horizon  of  localities  21  and  2g)  on  Hanford  Brook, 

St.  John  County,  New  Brunswick.     University  of  Toronto,  Canada.     (See  figure  Ig  for  back  view.) 
le  and  le'.  Top  and  side  views  of  a  broad  ventral  valve  from  Locality  2g,  Middle  Cambrian,  in  sandstones 

of  Division  Ibl  of  Matthew  on  Hanford  Brook,  St.  John  County,  New  Brunswick,  preserving  the 

foraminal  aperture.     U.  S.  Nat.  Mus.  Cat.  No.  35276e. 
If,  If,  and  If".  Top,  side,  and   back  views  of  a  specimen  with  a  relatively  small   apical    callosity  and 

vertical  false  area.     Middle  Cambrian  sandstones  of  Division  Ibl  (the  general  horizon  of  localities 

2f  and  2g)  on  Hanford  Brook,  St.  John  County,  New  Brunswick.  University  of  Toronto,  Canada. 
Ig.  Back  view  of  specimen  represented  by  figure  Id,  with  upper  portion  restored  from  another  specimen. 
Ih.  Cast  of  an  elongate  dorsal  valve  associated   with  the  shell  represented  by  figure  1.     L^.  S.  Nat.  Mus. 

Cat.  No.  3.5276f. 
li.  Partly  exfoliated  dorsal  valve  associated  with  the  specimen  represented   by  figure   le.     U.  S.  Nat. 

Mus.  Cat.  No.  35276g. 
Ik  and  Ik'.  Top  and  back  vaews  of   cast  of  dorsal  valve  associated  with  the  specimen  represented    by 

figure  le,  showing  large  cardinal  scars  and  strong  median  ridge.  U.  S.  Nat.  Mus.  Cat.  No.  35276h. 
2.  Ventral  valve  from  the  same  general  horizon  as  that  of  localities  2f  and  2g,  Middle  Cambrian  sandstones  of 

Division  Ibl  on  Hanford  Brook,  St.  John  County,  New  Brunswick.     University  of  Toronto,  Canada. 

Drawn  from  the  type  specimen  of  the  species;  it  was  figured  by  Matthew  [1886,  PI.  V,  figs.  7  and  7a] 

as  Li/igiilella  f  inflata. 
2a.  Ventral  valve  associated  with  the  specimen  represented   by  figure  2.     University  of  Toronto,  Canada. 

Specimen  figured  by  Matthew  [1895a,  PI.  V,  figs,  -i-^-c]  aa  Lingulella  f  inflata  ovalis. 

AcROTUYRA  PROAViA  (Matthew)   (p.  717). 

[PI.  LXXV,  fig.  3.] 

Figure  3.  Slender,  elongate  ventral  valve  from  Locality  131,  Middle  Cambrian  shaly  sandstones  of  E3a  of  Matthew's 
Etcheminian,  Dugald  Brook,  Cape  Breton,  Nova  Scotia.  University  of  Toronto,  Canada.  This 
specimen  was  first  illustrated  by  Matthew  [1901b,  fig.  1,  p.  303]  as  Acrothyra  pmavia  prima. 

3a  and  3a'.  Top  and  side  views  of  a  ventral  valve.     U.  S.  Nat.  Mus.  Cat.  No.  52052a. 

3b.  A  broader  form  of  the  ventral  valve  than  that  shown  by  figure  3.     U.  S.  Nat.  Mus.  Cat.  No.  52052b. 

3c.  A  ventral  valve  associated  with  specimen  represented  by  figure  3.     University  of  Toronto,  Canada. 

3d,  3d',  and  3d".  Top,  back,  and  side  views  of  a  ventral  valve  with  the  apex  broken  off.  Labeled  "A. 
proavia  var.;"  it  is  probably  the  variety  "crassa"  Matthew.  University  of  Toronto,  Canada.  Hori- 
zon and  locality  unknown. 

3e  and  3e'.  Top  and    side  views  of   a  broad  ventral  valve;  this  probably  represents  the  form  for  which 
Matthew  proposed  the  variety  crassa.    U.  S.  Nat.  Mus.  Cat.  No.  52052c. 
250 


U.  S.   GEOLOGICAL  SURVEY 


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MONOGRAPH   LI     PL.  LXXVI 


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FRANCES  WIESEB  DEL. 


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PLATE  LXXVI.  251 

AcROTHYRA  PROAViA  (Matthew) — Continued. 

Figure  31".  Ventral  valve.    U.  S.  Nat.  Mus.  Cat.  No.  .52052d. 

3g.  Posterior  \'iew  of  false  area  of  a  specimen  associated  with  the  specimen  represented  by  figure  3.  Univer- 
sity of  Toronto,  Canada. 

3h.  Posterior  view  of  false  area  of  a  much  broader  shell  than  that  represented  by  figure  3g.  U.  S.  Nat.  Mus. 
Cat.  No.  52052e. 

3i,  3k,  and  31.  Casts  of  ventral  valves  showing  cast  of  visceral  cavity.  U.  S.  Nat.  Mus.  Cat.  Nos.  62052f, 
52052g,  and  52052h,  respectively. 

3m.  Interior  of  a  ventral  valve.     U.  S.  Nat.  Mus.  Cat.  No.  520521. 

3n.  Interior  of  a  ventral  valve  with  the  apex  broken  away.     U.  S.  Nat.  Mus.  Cat.  No.  52052J. 

3o.  Two  ventral  valves  illustrating  effect  of  distortion  by  compression.     U.  S.  Nat.  Mus.  Cat.  No.  52052k. 

3p.  Interior  of  a  dorsal  valve  associated  with  many  specimens  of  this  species,  which  varies  in  outline  and 
internal  markings  from  all  other  specimens.  This  may  be  owing  to  elongation  and  compression  in 
the  matrix.    U.  S.  Nat.  Mus.  Cat.  No.  520521. 

3q.  Interior  of  dorsal  valve*    U.  S.  Nat.  Mus.  Cat.  No.  52052m-. 

3r  and  3s.  Casts  of  interior  of  dorsal  valves.    U.  S.  Nat.  Mus.  Cat.  Nos.  52052n  and  52052o,  respectively. 

3t.  Interior  of  dorsal  valve.     U.  S.  Nat.  Mus.  Cat.  No.  52052p. 

3u.  Exterior  and  side  outline  of  a  dorsal  valve.     U.  S.  Nat.  Mus.  Cat.  No.  52052q. 

With  the  exception  of  figures  3,  3c,  3d,  and  3g,  all  of  the  specimens  represented  by  figures  3,  3a-u  are  from  Locality 
lOq,  Middle  Cambrian  sandstone  below  the  waterfall  in  Division  E2b  of  Matthew's  [1903,  p.  21]  Etcheminian,  Dugald 
Brook.  Indian  River,  eastern  Cape  Breton,  Nova  Scotia. 

AcROTHYRA    MINOR    Walcott    (p.  717). 
(Text  flg.  59,  p.  717.) 

FiQUKES  4  and  4'.  Top  and  side  views  of  a  nearly  perfect  ventral  valve,  the  type  specimen.     U.  S.  Nat.  Mus.  Cat. 

No.  52050a. 
4a  and  4a'.  Top  and  aide  views  of  a  cast  of  the  interior  of  a  ventral  valve  that  had  a  large  apical  callosity. 

U.  S.  Nat.  Mus.  Cat.  No.  52050b. 
4b,  4b',  and  4b".  Top,  back,  and  side  views  of  a  cast  of  the  interior  of  a  ventral  valve.     IT.  S.  Nat.  Mus. 

Cat.  No.  52050c. 

The  specimens  represented  are  all  from  Locality  5b,  Middle  Cambrian  Langston  limestone  near  the  mouth  of 
Twomile  Canyon,  2  miles  (3.2  km.)  southeast  of  Malade,  Oneida  County,  Idaho. 


PLATE    LXXVII. 


253 


PLATE  LXXVII. 

cl.  Cardinal  scars.  s.  Median  septum, 

fp.  False  pedicle  groove.  vs.  Main  vascular  sinus, 

h.  Central  scars.  x".  Cast  of  apical  callosity. 

ACROTRETA    CONCENTRICA    Walcott   (p.  681). 

Figures  1,  1',  and  1".  Top,  side,  and  back  views  of  the  exterior  of  a  ventral  valve,  the  type  specimen.     U.  S.  Nat. 
Mus.  Cat.  No.  35266a. 
la  and  la'.  Top  and  side  views  of  a  partial  cast  of  the  interior  of  a  ventral  valve,  showing  the  base  of  strong 

vascular  sinuses  and  cardinal  scars.     U.  S.  Nat.  Mus.  Cat.  No.  35266b. 
lb.  Cast  of  a  compressed  dorsal  valve.     U.  S.  Nat.  Mus.  Cat.  No.  35266c. 

The  specimens  represented  are  all  from  Locality  96x,  Middle  Cambrian  limestone  1  mile  (1.6  km.)  north  of  Adairs- 
ville,  15  miles  (24.2  km.)  northwest  of  Cartersville,  Cartersville  quadrangle  (U.  S.  Geol.  Survey;,  Bartow  County, 
Georgia. 

AcROTRETA  BAiLEYi  Mattliew  (p.  676). 

Figures  2,  2',  and  2".  Top,  side,  and  back  views  of  a  slightly  distorted  ventral  valve.   Type  specimen,  (igiu-ed  by  Mat- 
thew [1886,  PI.  V,  figs.  13c  and  13d].     This  specimen  has  been  repeatedly  figured;  see  page  676  for 
record. 
2a.  Cast  of  a  distorted  dorsal  valve.     Specimen  figured  by  JIatthew  [1886,  PI.  V,  fig.  13].     The  specimen  has 

been  repeatedly  figured;  see  page  676  for  record. 
2b  and  2c.  Casts  of  the  interior  of  distorted  dorsal  valves. 
2d.  Interior  of  a  compressed  dorsal  valve. 
The  specimens  represented  are  all  from  Locality  300,  Middle  Cambrian  shaly  sandstones,  possibly  of  Di\'ision  Id 
of  Matthew,  on  Long  Reach,  St.  John  River.  Kings  County,  New  Brunswick.     They  are  in  the  collection  of  the  Uni- 
versity of  Toronto,  Canada. 

AcROTRETA    SEEBACHI    Wllloott   (p.  710). 

Figures  3,  3',  and  3".  Top,  back,  and  side  views  of  a  cast  of  the  interior  of   a  ventral  valve  from  Locality  8x, 

passage  beds  between  the  L^pper  Cambrian  and  the  Ordovician,  Ccratopyge  limestone  at  the  cement 

works  at  Slemmestad,  about  3  miles  (4.8  km.  t  .southwe.'^t  of  Christiania,  Norway.     U.  S.  Nat.  Mus. 

'    Cat.  No.  52172a.     This  is  the  type  specimen. 

3a,  3a',  and  3a".  Top,  side,  and  back  views  of  the  exterior  of  a  ventral  valve  associated  with  the  .specimen 

represented  l)y  figure  3.     U.  S.  Nat.  Mus.  Cat.  No.  52172b. 

AcROTRETA  PARVULA  (Wallerius)  (p.  699). 

Figures  4,  4',  and  4".  Top,  back,  and  side  views  of  ventral  vahe  from  Locality  3101.  pa.ssage  beds  between  the  Mid- 
dle and  Upper  Cambrian,  in  limestone  at  Borgholm,  Oeland  Island,  Sweden.     U.  S.  Nat.  Mus.  Cat. 
No.  35283a. 
4a.  Exterior  of  dorsal  valve,  associated  with  the  specimen  represented  by  figure  4.     V.  S.  Nat.  Mus.  ("at. 
No.  35283b. 

AcROTRETA    GEMMULA    MattllCW    (p.  686). 

[PI.  LXVI,  figs.  3.  3a-c.] 

Figures  5,  5',  and  5".  Top,  back,  and  side  views  of  the  exterior  of  a  ventral  valve  from  Locality  lOp.  Middle  Cam- 
brian sandstones  of  Division  E2b  of  Matthew's  Etcherainiaii  on  Dugald  Brook.  Indian  River.  Cape 
Breton.  Nova  Scotia.     U.  S.  Nat.  Mus.  Cat.  No.  52088a. 

5a,  5a',  and  5a".  Top,  back,  and  side  views  of  a  ventral  valve  showing  the  cast  of  the  surface  of  the  apical 
callosity.  Locality  lOp",  Middle  Cambrian  sandstone  on  the  small  brook  on  the  hill  between  the 
bridge  over  Indian  River  and  McPhees  Brook,  Cape  Breton,  Nova  Scotia.  U.  S.  Nat.  Mus.  Cat. 
No.  52088b. 

5b,  5b'.  and  5b".  Top,  back,  and  side  views  of  a  ventral  valve  a.ssocialed  witli  the  specimen  represented 
by  figure  5,  showing  cast  of  base  of  vascular  sinuses,  surface  of  apical  callosity,  and  pedicle  tube. 
U,  S.  Nat.  Mus.  Cat.  No.  52088c. 
254 


U.  S.   GEOLOGICAL  SURVEY 


MONOGRAPH   LI     PL.  LXXVII 


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PLATE  LXXVII.  255 

AcROTRETA  GEMMULA  Matthew — Continued. 

FiQWRBS  5c  and  5c'.  Top  and  side  views  of  a  ventral  valve  associated  with  the  specimen  represented  by  figure  5, 

that  has  a  more  erect  posterior  side  than  most  specimens.     U.  S.  Nat.  Mus.  Cat.  No.  52088d. 
5d  and  5d'.  Back  and  side  views  of  a  ventral  valve  associated  with  the  specimen  represented  by  figure  5, 

the  surface  of  which  has  lieen  roughened  by  the  impress  cjf  the  fine  grains  of  sand  in  the  matrix  so 

that  it  resembles  the  surface  characteristic  of  "  Acrotreta  papiUulu^'  MatUhevi^Acrothyra  sera.    U.  S. 

Nat.  Mus.  Cat.  No.  52088e. 
5e.  Side  view  of  a  ventral  valve  associated  with  the  specimen  represented  by  figure  5.  in  which  the  posterior 

side  curves  backward  a.s  in  Matthew's  figure  of  the  ventral  valve  [1903,  PI.  Ill,  fig.  4b].     U.  S.  Nat. 

Mus.  Cat.  No.  52088f. 
5f  and  5f'.  Top  and  side  views  of  thcexterior  of  a  dorsal  valve  associated  with  the  specimen  represented  by 

figure  5.     U.  S.  Nat.  Mus.  Cat.  No.  52088g. 

Acrotreta  babel  Barrande  (p.  676). 

Figures  6  and  6a.  Top  and  side  views  of  a  ventral  valve,  the  type  specimen,  from  Locality  303,  Lower  Ordovician, 
Etage  d3  at  Konigshof,  Bohemia.     Copied  from  Barrande  [1879b,  PI.   XCV,  figs,  vii;   2A  and  2B, 
respectively]. 
6b.  Cast  of  dorsal  valve  associated  with  specimen  represented  by  figures  (i  and  6a.     Copied  from  Barrande 
[1879b,  PI.  XCV,  fig.  vu:  2C]. 

Acrotreta?  minima  (Barrande)  (p.  695). 

Figure  7.  Top  view  of  ventral  \  alve,  the  type  specimen,  from  Locality  303d,  Lower  Ordovician,  Etage  dl  at  Swarow, 
Bohemia. 
7a.  Cast  of  dorsal  valve  associated  with  the  specimen  represented  by  figure  7. 

The  figures  are  both  copied  from   Barrande  [1879b.  PI.  XCV,  figs,  ii;   3A  and  lA,  respectively],  who  labeled 
them  "Obolus  f  minimus." 

Acrotreta  belti  (Davidson)  (p.  678). 

Figure  8.  Cast  of  the  interior  of  a  compressed  ventral  valve,  the  type  specimen,  from  Locality  306,  LTpper  Cambrian 
Lower  Tremadoc  shales  at  Craig-y-dinas,  North  Wales. 
8a.  Cast  of  the  interior  of  a  dorsal  valve  associated  with  the  specimen  represented  by  figure  8. 

The  figures  are  both  copied  from  Davidson  [1871.  PL  L.  figs.  16a  and  17a,  respectively].     The  same  specimens 
were  figiu-ed  by  Davidson  [1868,  PI.  XV,  figs.  27a  and  26a,  respectively],  both  as  Oholdla  bdti. 

Acrotreta  neboensis  Walcott  (p.  695). 

Figure  9.  Top  view  of  ventral  valve.     U.  S.  Nat.  Mus.  Cat.  No.  52130a. 

9a,  9a',  and  9a".  Top,  side,  and  back  views  of  the  exterior  of  a  ventral  valve,  the  type  specimen.     U.  S.  Nat. 

Mus.  Cat.  No.  52130b. 
9b.  Exterior  of  a  dorsal  valve,  showing  strong  median  sinus.     U.  S.  Nat.  Mus.  Cat.  No.  52130c. 

The  specimens  represented  are  all  from  Ix)cality  14t,  Middle  Cambrian  limestone  in  Mount  Nebo  Canyon,  3  miles 
(4.8  km.)  southeast  of  Mona,  Juab  County,  Utah. 

Acrotreta  nox  Walcott  (p.  696). 

Figures  10  and  10'.  Top  and  side  views  of  a  ventral  valve,  the  type  specimen,  from  Locality  lOv,  Upper  Cambrian 
shales  at  Fox  Glen,  about  8  miles  (12.8  km.)  east  of  Baraboo,  Sauk  County,  Wisconsin.  U.  S.  Nat. 
Mus.  Cat.  No.  52132a. 


PLATE    LXXVIII. 


62667°— VOL  51,  pt  2—12 17  257 


PLATE  LXXVIII. 

ac.  Apical  callosity.  h.  Central  muscle  scar, 

cl.  Cardinal  scar.  s.  Median  septum. 

fa.  False  area.  vs.  Main  vascular  sinus. 

(p.  False  pedicle  groove.  x".  Cast  of  apical  callosity. 

ACROTRETA    OPIIIRENSIS    DESCEXDEXS    Walcott   (p.  698). 

Figures  1,  V,  and  1".  Top,  side,  and  back  views  of  ventral  valve,  the  type  specimen.     U.  S.  Nat.  Mus.  Cat.  No.  .52143a. 
Copied  from  Walcott  [1908d,  PI.  IX,  figs.  1,  1',  and  1"]. 
la.  Posterior  portion  of  ventral  valve  showing  apex.     U.  S.  Nat.  Mus.  Cat.  No.  52143d. 
lb.  Dorsal  valve.     U.  S.  Nat.  Mus.  Cat.  No.  52143c. 
Ic.  Interior  of  a  dor.sal  valve.     U.  S.  Nat.  Mus.  Cat.  No.  52143b.     Copied  from  Walcott  [1908d,  PI.  IX,  fig.  la]. 

The  specimens  represented  are  all  from  Locality  30n,  Middle  Cambrian  limestone  in  Ic  of  the  Weeks  limestone,  on 
the  north  side  of  Weeks  Canyon,  about  4  miles  south  of  Marjum  Pass.  House  Range  [Walcott,  1908f,  PI.  XIII],  Millard 
County,  Utah. 

AcROTRETA    MARJUJIEXSIS    Walcott  (p.  693). 

Figures  2,  2',  and  2".  Top,  side,  and  back  views  of  ventral  valve,  the  type  specimen,  from  Locality  lln.  Middle 
Cambrian  limestone  in  la  of  the  Marjum  limestone  in  the  long  cliff  2  mUes  (3.2  km.)  southeast  of 
Marjum  Pass,  Hou.se  Range,  Utah.  U.  S.  Nat.  Mus.  Cat.  No.  .52116a.  Copied  from  Walcott  [1908d, 
PI.  IX,  figs.  2,  2',  and  2"].  Two  specimens,  both  on  the  same  hand  specimen  as  the  shell  represented 
by  figure  2,  were  also  used  in  drawing  these  figures. 

2a.  Top  \ie\v  of  a  nearly  circular  ventral  valve  from  Locality  33d,  Upper-Cambrian  limestone  at  the  base  of 
the  first  high  point  southwest  of  the  J.  J.  Thomas  ranch,  Fish  Spring  Range,  LTtah.  U.  S.  Nat.  Mus. 
Cat.  No.  52117a. 

2b.  Broken  dorsal  valve  associated  with  the  specimen  represented  by  fig:ure  2.  U.  S.  Nat.  Mus.  Cat.  No. 
521 16c.       Another  specimen  (Cat.  No.  52116e)  was  used  to  restore  certain  portions  of  this  figure. 

2c.  Interior  of  dorsal  valve  associated  with  the  specimen  represented  by  figure  2.  U.  S.  Nat.  Mus.  Cat.  No. 
52116b.     Copied  from  Walcott  [1908d,  PI.  IX,  fig.  2a]. 

2d.  Side  view  of  median  septum  of  a  dorsal  valve  associated  with  the  specimen  represented  by  figure  2.  L'.  S. 
Nat.  Mus.  Cat.  No.  52116d. 

ACROTRETA    ULRICHI    Walcott  (p.  71-1). 

Figures  3,  3',  and  3".  Top,  side,  and  back  views  of  ventral  valve  from  Locality  12p,  Upper  Cambrian  limestones  of 
the  Reagan  sandstone,  at  the  northwest  extremity  of  the  Arbuckle  Mountains,  about  4  mUes  (6.4  km.) 
east  of  Homer,  Carter  County,  Oklahoma.  I^.  S.  Nat.  Mus.  Cat.  No.  52180a.  Copied  from  Walcott 
[1908d,  PL  IX,  figs.  3,  3',  and  3"].     This  is  the  type  specimen. 

ACROTRETA    BELLATULA    Walcott  (p.  077). 

FiGURE.s  4,  4',  and  4".  Top,  side,  and  back  views  of  ventral  valve,  the  type  specimen.     U.  S.  Nat.  Mus.  Cat.  No. 

52072a.     Copied  from  Walcott  [1908d,  PI.  IX,  figs.  4,  4',  and  4"j. 
4a.  Extcriorof  dorsal  valve.     U.  S.  Nat.  Mus.  Cat.  No.  52072e. 
4b.  Portion  of  interior  of  ventral  valve.     U.  S.  Nat.  Mus.  Cat.  No.  o2072b.     Copied  from  Walcott  [1908d,  PL 

IX,  fig.  4a.] 
4c.  Cast  of  interior  of  ventral  valve.     U.  S.  Nat.  Mus.  Cat.  No.  52072d. 
4d.  Cast  of  interior  of  dorsal  valve.     V.  S.  Nat.  Mus.  Cat.  Xo.  .52072c.     Another  specimen  (catalogue  No. 

520721)  was  used  to  restore  certain  portions  of  this  figure.     Copied  from  Walcott  [1908d,  PL  IX,  fig.  4b]. 

The  specimens  represented  are  all  from  Locality  lOz,  Middle  Cambrian  limestones  in  la  of  the  Marjum  limestone 
in  the  long  cliff  southeast  of  Marjum  Pass  [Walcott,  190Sf,  p.  179,  and  Pis.  XIII  and  XV],  House  Range,  Utah.  ■ 
258 


U.   S.  GEOLOGICAL  SURVEY 


MONOGRAPH   LI     PL.  LXXVIII 


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FRANCES  WIESEH  DEL. 


MeVlOIVPE     CO     BOSTON 


PLATE  LXXVIII.  259 

LiNNARSSONELLA    GIRTYI    Walcott  (p.  666). 
[PI.  LXXIX,  figs.  1,  la-r.) 

Figures  5  and  5'.  Top  and  side  views  of  ventral  valve  from  Locality  32t,  Ujjper  Cambrian  limestone  in  Fandango 
Spring  Canyon  on  the  east  side  of  the  Dugway  Range,  about  5  miles  (8  km.)  north  of  where  the  stage 
road  between  Vernon  and  Deep  Creek  crosses  the  divide,  Tooele  County,  Utah.  U.  S.  Nat.  Mus.  Cat. 
No.  52195a. 
5a.  Exterior  view  of  dor.sal  valve  associated  with  the  specimen  represented  by  figure  5.  U.  S.  Nat.  Mus.  Cat. 
No.  52195b, 

LiNNARSSONELLA    TRANSVERSA    Walcott  (p.  670). 

Figures  6,  6',  and  6".  Top,  side,  and  back  views  of  ventral  valve  from  Locality  30j,  Upper  Cambrian  limestone  in  le 
of  the  Orr  formation  on  Orr  Ridge,  about  5  miles  (8  km.)  south  of  Marj'um  Pass  [Walcott,  1908f,  p.  176 
and  PI.  XIII],  House  Range,  Utah.  U.  S.  Nat.  Mus.  Cat.  No.  52201a.  Figures  6  and  6'  are  copied 
from  Walcott  [1908d,  PI.  IX,  figs.  6  and  6'].  This  is  the  type  specimen. 
6a,  6b,  and  6c.  Partly  exfoliated  dorsal  valves  associated  with  the  specimen  represented  by  figure  6.  U.  S. 
Nat.  Mus.  Cat.  Nos.  52201b,  52201c,  and  52201d,  respectively. 

LiNNARSSONELLA    NITENS    Walcott  (]).  669). 

Figures  7,  7',  and  1" .  Top,  side,  and  back  views  of  \-entral  valve  from  Locality  31t,  Upper  Cambrian  limestone  in  Id 
of  the  Orr.formation  on  Orr  Ridge,  about  5  miles  (8  km.)  south  of  Marjum  Pass  [Walcott  lOOSf,  p.  176 
and  PI.  XIII],  House  Range,  Utah.  U.  S.  Nat.  Mus.  Cat.  No.  52198a.  Figures  7  and  T  are  copied 
from  Walcott  [1908d,  PI.  IX,  figs.  7  and  7'].  This  is  the  type  specimen. 
7a.  Partly  exfoliated  dor.sal  valve  associated  with  the  specimen  represented  by  figure  7.  U.  S.  Nat.  Mus. 
Cat.  No.  52198b. 

LiNNARSSONELLA    MODESTA    Walcott  (p.  66.S). 

Figures  8,  8',  and  8".  Top,  side,  and  back  views  of  ventral  valve  from  Locality  31t,  Upper  (.'ambrian  limestone  in 

Id  of  the  Orr  formation  on  Orr  Ridge,  dbout  5  miles  (8  km.)  south  of  Marjum  Pass  [Walcott,  1908f,  p. 

176and  PI.  Xlll],  House  Range,  Utah.     U.  S.  Nat.  Mus.  Cat.  No.  53G79a.     Figures 8  and  8' are  copied 

from  Walcott  [190Sd,  PI.  IX,  figs.  8  and  8']. 
8a.  A  more  acuminate  ventral  valve  than  that  represented  by  figure  8.     U.  S.  Nat.  Mus.  Cat.  No.  52197e. 
8b  and  Sb'.  Exterior  and  back  views  of  a  partly  exfoliated  ventral  valve.     U.  S.  Nat.  Mus.  Cat.  No.  52197b. 
8c  and  8d.  Partly  exfoliated  ventral  valves.     U.  S.  Nat.  Mus.  Cat.  Nos.  52197c  and  52rj7d,  respectively. 
8e.  Interior  of  ventral  valve,  the  type  specimen.     U.  S.  Nat.  Mus.  Cat.  No.  52197a.     Copied  from  Walcott 

[1908d,  PI.  IX,  fig.  8a]. 
8f.  Interior  of  dorsal  valve.     U.  S.  Nat.  Mus.  Cat.  No.  52197f. 

The  spei'imens  represented  by  figures  8a-f  are  from  Locality  30k,  25  feet  below  Locality  31t  (fig.  8),  at  the  same 
place  on  Orr  Ridge. 

LiNNARSSONELLA    URANIA    Walcott  (p.  670). 

Figure  9.  Partly  exfoliated  dorsal  valve.     U.  S.  Nat.  Mus.  Cat.  No.  52202d. 

9a,  9a',  and  9a".  Top,  side,  and  back  views  of  a  partly  exfoliated  ventral  valve.     U.  S.  Nat.  Mus.  Cat.  No. 

52202a.     Figure  9a  is  copied  from  Walcott  [1908d,  PL  IX,  fig.  9].     This  is  the  type  specimen. 
9b.  Interior  of  ventral  valve.     U.  S.  Nat.  Mus.  Cat.  No.  52202c. 
9c.  Interior  of  dorsal  valve.     U.  S.  Nat.  Mus.  Cat.  No.  52202b.     Copied  from  Walcott  [1908d,  PL  IX,  fig.  9a]. 

The  specimens  represented  are  all  from  Locality  55u,  Middle  Cambrian  limestone  0.25  mile  (0.4  km.)  below  the 
Maxfield  mine,  in  Big  Cottonwood  Canyon,  on  the  west  side  of  the  Wasatch  Mountains,  southeast  of  Salt  Lake  City,  Utah. 


PLATE   LXXIX. 


261 


PLATE  LXXIX. 


a.  Central  lateral  space  of  area, 
a'.  Outer  lateral  space  of  area, 
ol.  Cardinal  scar. 

f.  Flexure  lino  of  an'u. 
fa.  False  area. 
h.  Central  muscle  scar. 


j.  Anterior  lateral  muscle  scar. 

s.  Median  septum  or  ridge. 

V.  Visceral  area, 
vs.  Main  vascular  sinus. 

X.  Foraminal  aperture, 
x".  Cast  of  apical  callosity. 


LiNNARSSONELLA    GIRTYI    AValcott    (\).   666). 
[Pi.  LXXVIII,  figs.  6,  5a.] 

Figure  1.  Exterior  of  ventral  valve  with  side  \-iew  of  same,  the  type  specimen.     U.  S.  Nat.  Mus.  Cat.  No.  35287a. 
la,  la',  and  la".  Exterior,  posterior,  and  side  views  of  ventral  valve.     The  archini;  of  the  cardinal  line  of  the 

area  is  well  shown  in  this  shell.    U.  S.  Nat.  Mus.  Cat.  No.  352.S7q. 
lb  and  lb'.  Exterior,  side,  and  posterior  views  of  ventral  valve.    The  straight,  horizontal  cardinal  lino  of  the 

area  is  a  feature  of  this  shell.    U.  S.  Nat.  Mus.  Cat.  No.  35287b. 
Ic  and  Ic'.  Exterior,  with  side  and  posterior  views,  of  ventral  valve  with  nearly  straight  cardinal  line  of  shell 

and  area.    U.  S.  Nat.  Mus.  Cat.  No.  35287c.     Compare  the  outline  and  slope  of  the  area  in  this  speci- 
men with  that  showTi  in  figures  1  and  la . 
Id  and  lo.  Exterior  and  side  ^■iew^  of  two  ventral  valves.     U.  S.  Nat.  Mus.  Cat.  Nos.  3.5287d  and  35287e, 

respectively. 
If-lj.  Exterior  and  side  views  of  dorsal  valves,  to  illustrate  variation  in  outline  and  convexity  of  valve.     U.  S. 

Nat.  Mus.  Cat.  Nos.  35287f-j,  respectively.  ■ 
Ik.  Cast  of  interior  of  ventral  valve  with  side  outline.     I".  S.  Nat.  Mus.  Cat.  No.  35287k. 
Ik'.  Posterior  view  of  specimen  represented  by  figure  Ik,  showing  po.sterior  outline  of  cardinal  scars  and  the 

vascular  canals;  also  base  of  cast  of  foramen.     U.  S.  Nat.  Mus.  Cat.  No.  35287k. 
1  1.  Cast  of  the  interior  and  side  outline  of  a  dorsal  valve.    This  illustrates  all  that  is  known  of  the  interior 

of  this  valve  from  the  casts.     An  interior  from  another  locality  is  shown  by  figure  Ir.     U.  S.  Nat. 

Mus.  Cat.  No.  3.5287  1. 
Im-lp.  Casts  of  the  interior  and  side  outlines  of  ventral  valves  that  illustrate  the  variation  in  size  and  position 

of  the  cardinal  scars  and  ^•ascular  canals.     U.  S.  Nat.  Mus.  Cat.  Nos.  35287m-p,  respectively. 

The  specimens  represented  by  figures  1,  la-p  are  from  Locality  88a,  Middle  Cambrian  limestone  about  100  feet 
(30.5  m)  above  the  quartzilic  sandstone  at  the  base  of  the  Cambrian,  in  the  northern  suburbs  of  Deadwood,  Black 
Hills,  South  Dakota. 

FiGtjREs  Iq,  Iq',  and  Iq".  Top,  side,  and  back  views  of  exterior  of  ventral  valve  that  is  more  elevated  than  usual 
and  which  has  a  very  high  false  area.  U.  S.  Nat.  Mus.  Cat.  No.  52188a. 
Ir.  Interior  of  dorsal  valve  on  which  the  area  is  preserved,  also  the  depressions  of  the  cardinal  scars  and  a 
low,  broad,  median  ridge,  but  no  traces  of  the  central  or  anterior  lateral  scars.  This  is  the  only  speci- 
men found  showing  the  interior  of  the  valve,  except  in  the  form  of  casts  (fig.  1 1).  V .  S.  Nat.  Mus. 
Cat.  No.  52188b. 

The  specimens  represented  by  figiures  Iq  and  Ir  are  from  Locality  9p,  Upper  Cambrian,  about  IfiO  feet  (48.8  m) 
above  the  porphyry  contact  in  the  lunestone  of  the  Reagan  sandstone,  in  SE.  \  NE.  J  sec.  2,  T.  4  N.,  R.  13  W.,  about 
15  miles  (24.2  km.)  northwest  of  Fort  Sill,  Comanche  County,  Oklahoma. 

LiNNARSSONKLLA  MiNUTA  (Hall  and  Whitfield)  (p.  667). 

Figure  2.  Interior  of  a  ventral  valve,  showing  cardinal  scars  and  foramen.     V .  S.  Nat.  Mus.  Cat.  No.  24553a. 

2a  and  2a'.  Cast  of  the  interior  of  a  ventral  valve  with  side  and  ixisierior  outlines.     U.  S.  Nat.  Mus.  Cat.  No. 

24553b. 
2b.  Cast  of  the  interior  of  a  dorsal  valve  and  side  view  of  game.     U.  S.  Nat.  Mus.  Cat.  No.  24553c. 

The  specimens  represented  are  all  from  Locality  313h,  T'pper  Cambrian  sandy  shale  on  Hamburg  Ridge,  Eureka 
district,  Nevada.     They  all  occur  on  the  same  hand  specimen  wilh  the  shells  reprosenlcd  by  Hall  and  ^\■hitlield  [1877, 
PI.  I,  figs.  3  and  4],  but  the  latter  shells,  which  include  the  type,  are  not  figured  in  this  monograiih. 
262 


U.  S.   GEOLOGICAL  SURVEY 


MONOGRAPH   LI     PL.   LXXIX 


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FRANCES  WIESEH  DEL. 


MELIOirPE    CO    BOSTOW 


PLATE  LXXIX.  263 

LiNNARSSONELLA    TENNESSEENSIS    Walcott  (p.  669). 

Figures  3  and  3'.  Exterior  and  side  views  of  a  ventral  valve  from  I^ocality  13,  Middle  Cambrian  limestones  of  the 
Rome  formation  1.5  miles  (2.4  km.)  east  of  Post  Oak  Springs  [Hayes,  1S94,  areal  geology  sheet],  Roane 
County,  Tennessee.    U.  S.  Nat.  Mus.  Cat.  No.  35289a.    This  is  the  type  specimen. 

3a.  Cast  of  the  exterior  of  a  ventral  valve  from  Locality  107b,  Middle  Cambrian  shales  in  the  Rome  formation 
in  Bull  Run,  northwest  of  Copper  Ridge  [Keith,  1896b,  areal  geology  sheet],  11  miles  northwest  of 
Knoxville,  Tennessee.    U.  S.  Nat.  Mus.  Cat.  No.  3528Sa. 

3,  3b',  and  3c,  3c'.  Top  and  back  views  of  casts  of  ventral  valves  associated  with  the  specimen  represented 
by  fig.  3.     U.  S.  Nat.  Mus.  Cat.  Nos.  35289b  and  35289c,  respectively. 

3d,  3e,  3f,  and  3g.  Casts  of  the  interior  of  ventral  valves  associated  with  the  specimen  represented  by  figure 
3a.  U.  S.  Nat.  Mus.  Cat.  Nos.  352S8b,  35288c,  35288g,  and  3528Sh,  respectively.  Figures  3f  and  3g 
(with  fig.  3k)  represent  the  specimens  that  were  referred  to  Meehina  prima  (see  p.  669). 

3h,  3j,  and  3k.  Casts  of  interior  of  dorsal  valves  associated  with  the  specimen  represented  by  figure  3a.  U.  S. 
Nat.  Mus.  Cat.  Nos.  352S8d,  35288e,  and  352881,  respectively.  Another  specimen  (Cat.  No.  35288f) 
was  used  to  restore  certain  portions  of  this  figure.  Figures  3k,  3f,  and  3g  represent  the  forms 
that  were  refen-ed  to  Meekina  prima  (see  p.  669). 

3i.  Cast  of  interior  of  dorsal  valve  associated  with  the  specimen  represented  by  figure  3.  U.  S.  Nat.  Mus. 
Cat.  No.  35289d. 

ACROTRETA    SPINOSA    Walcott  (p.  713). 

Figures  4,  4',  and  4".  Top,  side,  and  back  views  of  a  ventral  valve.     V.  S.  Nat.  Mus.  Cat.  No.  52176a. 

4a.  Top  view  of  a  ventral  valve,  with  the  apex  in  front  of  the  posterior  margin.     U.  S.  Nat.  Mus.  Cat.  No. 

52176b. 
4b.  Top  view  of  a  ventral  valve,  the  type  specimen,  with  the  apex  overhanging  the  posterior  margin,  and 

showing  spinose  surface.     V .  S.  Nat.  Mus.  Cat.  No.  5217Gc. 
4c.  Exfoliated  ventral  valve,  showing  cast  of  the  apical  callosity  and  main  trunks  of  the  vascular  sinuses. 

U.  S.  Nat.  Mus.  Cat.  No.  52176d. 
4d.  Exfoliated  ventral  valve  from  Locality  62,  Upper  Cambrian  limestone  in  the  Dunderberg  shale  [W'alcott, 

1908f,  p.  184],  in  canyon  immediately  north  of  Adams  Hill,  Eureka  district,  Nevada.     V .  S.  Nat.  Mus. 

Cat.  No.  52177a. 
4e.  Cast  of  interior  of  a  dorsal  valve.     U.  S.  Nat.  Mus.  Cat.  No.  52176e. 
4f.  Exterior  of  a  dorsal  valve.     U.  S.  Nat.  Mus.  Cat.  No.  52176f.     (See  fig.  4g.) 
4g.  Enlargement  of  the  surface  of  the  specimen  represented  by  figure  4f,  to  illustrate  spinose  character  of 

the  outer  shell.     IT.  S.  Nat.  Mus.  Cat.  No.  52176f. 

With  the  exception  of  figure  4d,  the  specimens  represented  are  all  from  Locality  61,  Upper  Cambrian  limestone 
in  the  Dunderberg  shale,  a  little  south  of  the  Hamburg  mine.  Eureka  district,  Nevada. 

AcROTRETA??    CANCELLATA    Walcott  (p.  679). 

Figures  5  and  5'.  Top  and  side  \dews  of  the  type  specimen,  a  ventral  valve,  from  Locality  205,  passage  beds  between 
the  tapper  Cambrian  and  the  Ordovician,  siliceous  limestones  on  Round  top  Mountain,  Eureka  dis- 
trict, Nevada.     U.  S.  Nat.  Mus.  Cat.  No.  52079a. 
5a.  Enlargement  of  outer  surface  (X20)  of  the  specimen  represented  by  figure  5. 

ACROTRETA    ATTENTJATA    Meek  (p.  675). 

[PI.  LXIV,  flgs.  1,  la-o.] 

Figure  6.  Interior  of  a  ventral  valve.    U.  S.  Nat.  Mus.  Cat.  No.  52068a. 
6a.  Interior  of  a  ventral  valve.     U.  S.  Nat.  Mus.  Cat.  No.  .5r206Sb. 

The  specimens  represented  are  both  from  Locality  3x,  Middle  Cambrian  limestone  in  Id  of  the  Marjum  limestone, 
2.5  miles  (4km.)  east  of  Antelope  Springs,  in  ridge  east  of  Wheeler  Amphitheater,  House  Range,  Utah. 


PLATE   LXXX. 


265 


PLATE  LXXX. 

cl.  rardinal  scar.  v.  Visceral  area. 

fa.  False  area.  v.s.  Main  va-scular  sinus. 

fp.   False  pedicle  irroove.  x'.  fast  of  foraminal  tube. 

AcROTiiYRA  sioxATA  Matthew  (p.  719). 

Figure  1.  Ventral  valve  from  Locality  344k,  Middle  Cambrian  sandstones  of  Division  Elb  of  Matthew's  Etcheminian, 
.  Dugald  Brook,  Cape  Breton,  sliowing  cast  of  visceral  area.  University  of  Toronto,  Canada.  Type 
specimen,  figured  by  Matthew  [1902b,  PI.  XIII,  fig.  2b]. 

la.  Broad  form  of  ventral  valve  from  Locality  lOp,  Middle  Cambrian  sandstones  of  Division  E2b  of  Matthew, 
on  Dugald  Brook,  Indian  River,  Cape  Breton,  Nova  Scotia.     U.  S.  Nat.  Mus.  Cat.  No.  520.57a. 

lb.  Compressed,  nearly  circular  ventral  valve  associated  with  the  specimen  represented  by  figure  la.  U.  S. 
Nat.  Mus.  Cat.  No.  52057b. 

Ic.  Partly  exfoliated  dorsal  ^ah-e  from  Locality  lOp,  Middle  Cambrian  sandstones  of  Division  E2b  of  Mat- 
thew, on  Dugald  Brook,  Indian  River,  Cape  Breton,  Nova  Scotia.     U.  S.  Nat.  Mus.  Cat.  No.  52057c. 

Id.  Side  outline  of  a  ventral  valve  from  the  locality  represented  by  figure  1.  University  of  Toro.ito,  Canada. 
Specimen  figured  by  Matthew  [1902b,  Pi.  XIII,  fig.  2c]. 

ACROTHYRA    SIGNATA    PRIMA    llattliew   (p.   720). 

Figure  2.  Ventral  valve  showing  cast  of  visceral  area.     University  of  Toronto,  Canada.     Type  specimen,  figured  by 
Matthew  [1902b,  PI.  XIII,  fig.  lb]. 
2a.  Top,  side,  and  back  views  of  a  narrow  form  of  ventral  valve.     U.  S.  Nat.  Mus.  Cat.  \o.  52059a. 
2b.  Side  outline  of  a  ventral  valve.     University  of  Toronto,  Canada.     Sp->cimen  figured  by  Matthew  [1902b, 
PI.  XIII,  fig.  Ic]. 
The  specimens  represented  are  all  from  Locality  13k.  Middle  Cambrian  shales  of  Matthew's  Coldbrook,  on  Dugald 
Brook,  Indian  River,  Cape  Breton,  Nova  Scotia. 

AcROTHYRA  SIGNATA  ORTA  Matthew  (p.  719). 

Figure  3.  Exterior  \'iew  of  ventral  valve  from  Localit>-  13d",  Middle  Cambrian  sandstones  between  Di\-isions  E2a 
and  E2b  of  Matthew's  Etcheminian,  on  Dugald  Brook,  Cape  Breton,  Nova  Scotia.  U.  S.  Nat.  Mus. 
Cat.  No.  5205Sa. 
3a.  A  broken  shell  showing  cast  of  visceral  area  from  Locality  3441,  Middle  Cambrian  sandstones  of 
Division  E2c  of  Matthew's  Etcheminian,  Dugald  Brook,  Cape  Breton.  University  of  Toronto, 
Canada.  Type  specimen, "figured  by  Matthew  [1902b,  PI.  XIII,  fig.  4a]. 
3b.  Side  outline^of  a  ventral  valve  from  the  locality  represented  by  figure  3a.  University  of  Toronto, 
Canada.     Specimen  figured  by  Matthew  [1902b,  PI.  XIII,  fig.  4c]. 

ACROTHYRA   SERA    (Mattliew)    (p.  718). 

Figure  4.  Ventral  valve,  somewhat  compressed,  from  Locality  13t",  Middle  Cambrian  sandstones  of  Division  Elcand 

Eld  on  Dugald  Brook,  Cape  Breton,  Nova  Scotia.     L".  S.  Nat.  Mus.  Cat.  No.  52054a. 
4a,  4a',  and  4a".  Top,  side,  and  back  views  of  a  typical  form  of  ventral  valve  associated  with  the  specimen 

represented  by  figure  4.     U.  S.  Nat.  Mus.  Cat.  No.  52054b. 
4b.  Interior  of  a  dorsal  valve  (locality  unknowTi).     University  of  Toronto,  Canada. 
4c.  Side  outline  of  a  ventral  valve  from  Locality  344g,  Middle  Cambrian  shales  of  Division  Elc  of  Matthew's 

Etcheminian,  Dugald  Brook,  Cape  Breton.     L'niversity  of  Toronto,  Canada     Specimen  figured  by 

Matthew  [1902b,  PI.  XIII,  fig.  3c]  as  Acrothyra  (siffnata)  sera. 
5,  5',  and  5".  Top,  .side,  and  back  views  of  ventral  valve  associated  with  tlic  s])ecimen  represented  by  figure  4. 

U.  S.  Nat.  Mus.  Cat.  No.  52054c. 
5a.  Ventral  valve  a,ssociated  with  the  specimen  represented  by  figure  4,  showing  cast  of  \-isceral  area.     U.  S. 

Nat.  Mus.  Cat.  No.  52054d. 
5b.  Interior  of  ventral  valve  showing  elevated  ridge  about  foraminal  tube.     Locality  lOp,  Middle  Cambrian 

sandstone  in   Di\-i8ion   E2b  on   Dugald  Brook,  Cape  Breton,  Nova  Scotia.     U.  S.  Nat.  Mus.  Cat. 

No.  58306. 
266 


U.  S.   GEOLOGICAL  SURVEY 


MONOGRAPH   LI     PL.LXXX 


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4 

6 
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FRANCES  WiESER  DEL. 


3  «' 


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'V 


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HtLiorvce   . 


PLATE  LXXX.  267 

AcROTHYRA  SERA  Matthew — Continued. 

Figure  5c.  Cast  of  interior  of  a  shell  associated  with  the  specimen  represented  by  figure  4  showing  cast  of  foraminal 
tube.     U.  S.  Nat.  Mus.  Cat.  No.  52054e. 
5d.  Exterior  of  dorsal  valve  associated  with  the  specimen  represented  by  figure  4.     U.  S.  Nat.  Mus.  Cat.  No. 
52054f. 

Figures  5,  5a-d  are  drawn  from  typical  forms  of  Acrothyra  signata  tarda  of  Matthew. 

Figures  6,  6',  and  6".  Top,  side,  and  back  views  of  a  ventral  valve  from  Locality  13k,  Middle  Cambrian,  shales  of 
Matthew's  Coldbrook,  Dugald  Brook,  Cape  Breton.  University  of  Toroulo,  Canada.  Specimen 
figured  by  Matthew  [1902b,  PI.  XV,  figs.  2a  and  2b]  as  Acrolreia  papillala. 

6a.  Ventral  valve  with  apex  of  shell  broken  away  so  as  to  show  the  cast  of  the  foraminal  tube,  a.ssociated  with 
the  specimen  represented  by  figure  4.     U.  S.  Nat.  Mus.  Cat.  No.  52054g. 

6b  and  6b'.  Dorsal  valve  with  side  outline.     U.  S.  Nat.  Mus.  Cat.  No.  52054h. 

6c.  Cast  of  interior  of  dorsal  valve.     Compare  with  figure  4b.     U.S.  Nat.  Mus.  Cat.  No.  52054i. 

6d  and  6d'.  Top  and  side  views  of  a  cast  of  the  interior  of  a  ventral  valve  with  elongate  visceral  area.  U.  S. 
Nat.  Mus.  Cat.  No.  520.54J. 

6e.  Interior  of  a  ventral  valve  with  elongate  \'isceral  area.     U.  S.  Nat.  Mus.  Cat.  No.  520.54k. 

6f,  6g,  and  6h.  Ventral  valves  illustrating  variation  in  form  and  length  of  visceral  area.  V .  S.  Nat.  Mus.  Cat. 
Nos.  520541,  52054m,  and  52054n,  respectively. 

6i.  Ventral  valve  from  Locality  13k,  Middle  Cambrian,  shales  of  Matthew's  Coldbrook,  on  Dugald  Brook,  Cape 
Breton,  Nova  Scotia.     V.  S.  Nat.  Mus.  Cat.  No.  52055c. 

The  specimens  represented  by  figures  6,  6a-i  are  typical  forms  of  "Acrotrela  papiUata"  of  Matthew.  With  the 
exception  of  figures  6  and  6i  all  of  the  specimens  are  from  Locality  13t",  Middle  Cambrian  .sandstones  of  Di\'isions  Elc 
and  Eld  of  Matthew  on  Dugald  Brook,  Cape  Breton,  Nova  Scotia. 

Figures  7  and  7a.  Top  and  side  views  of  a  ventral  valve  associated  with  the  specimen  represented  by  figure  6i.     U.  S. 
Nat.  Mus.  Cat.  No.  520.55a. 
7b.  Exterior  of  dorsal  valve  associated  with  the  specimen  represented  by  figure  6i.     U.  S.  Nat.  Mus.  Cat. 
No.  52055b. 
The  specimens  represented  by  figures  7,  7a-b  are  typical  furms  of  "'Acrotrela  papillala  prima  "  of  Matthew. 

Figures  8,  8',  and  8".  Top,  back,  and  side  views  of  a  shell  somewhat  doubtfully  referred  to  this  species  from  Locality- 
13p,  Middle  Cambrian  sandstones  40  feet  above  division  E2a  of  Matthew,  on  Dugald  Brook,  Cape  Bre 
ton,  Nova  Scotia.     U.  S.  Nat.  Mus.  Cat.  No.  52056a. 


PLATE    LXXXI. 


269 


PLATE  LXXXI. 

a.  Cardinal  area.  pc.  Pedicle  furrow. 

cf.  Closed  forainiiial  tube  (see  p.  t'i29).  pi.  rialform. 

cl.  Cardinal  scar.  pi'.  Central  ridge  o(  platform, 

h.  Central  mu.scle  scar.  s.  Median  ridge. 

i.  Transmedian  muscle  scar.  t.  Cardinal  process  of  dorsal  valve  (see  p.  505). 

j.  Anterior  lateral  muscle  scar.  vs.  Vascular  sinus. 

Ik.  Outside  and  middle  lateral  muscle  scars.  x.  Cavity  beneath  platform. 
m.  Muscle  scars  on  front  face  of  platform. 

ScHizoPHOLis  RUGOSA  Waageii  (p.  609). 

[PI.  I,  fig.  4c.] 

Figures  1,  la,  and  lb.  Top,  side,  and  back  views  of  the  tj-pe  specimen,  a  ventral  valve.     Geol.  Survey  India  Cat. 
No.  3/790.     Specimen  figured  by  Waagen  [1885,  PI.  LXXXVI,  figs.  4a-d;  and  1891,  PI.  II,  figs.  12a-c]. 
Ic.  Exterior  \-iew  of  dorsal  valve.    Geol.  Survey  India  Cat.  No.  3/789.     Specimen  figured  by  Waagen  [1885, 
PL  LXXXVI,  figs.  3a-b;  and  1891,  PI.  II,  figs.  14a-b]. 

The  specimens  represented  are  all  from  Locality  357c,  Middle  Cambrian,  lower  portion  of  the  ■'  Neobolus  beds"  of 
the  Khussak  group,  in  purplish-colored,  fine-grained,  micaceous  sandstone  near  the  fresh-water  springs  in  a  gorge  above 
the  salt  mines  at  Kiura  (Khewra),  Salt  Range,  India. 

Neobolus  warthi  Waagen  (p.  566). 

[Text  figs.  4TA-B,  p.  SG7,  and  PI.  I,  figs.  3,  4.4a-b,  5,  and  5a.] 

Figure  2.  View  of  a  partly  exfoliated  ventral  valve.     Geol.  Survey  India  Cat.  No.  3/783.     Specimen  figured  by 

Waagen  [1885,  PI.  LXXXV,  figs.  3a-b;  and  1891,  PL  II,  figs.  3a-b]. 
2a.  Compressed  ventral  valve.     Geol.  Survey  India  Cat.  No.  3/787.     Specimen  figured   by  AVaagen   [1885, 

PL  LXXXVI,  figs,  la-b]  as  Davidsonella  squama,  and  [1891,  PI.  II,  figs.  6a-b]  as  Neobolus  icarthi. 
2b  and  2c.  Side  and  back  views  of  a  ventral  valve  showing  supposed  foraminal  aperture.     (See  p.  566.) 

This  shell  is  on  the  same  piece  of  rock  as  the  dorsal  valve  represented  by  figure  2d. 
2d.  Exterior  view  of  dorsal  valve.     Geol.  Survey  India  Cat.  No.  3/784.     Specimen  figured  by  Waagen  [1885, 

PL  LXXXV,  figs.  4a-b;  and  1891,  PL  II,  figs.  4a-b]. 
2e.  View  of  the  interior  of  a  ventral  valve.     Geol.  Survey  India  Cat.  No.  3/786.     Specimen  figured  by  Waagen 

[1885,  PL  LXXXV,  fig.  5;  and  1891.  PL  II.  fig.  3c]. 
2f.   View  of  the  interior  of  a  dorsal  valve,  the  type  specimen.     Geol.  Survey  India  Cat.  No.  3/785.    Specimen 

figured  by  Waagen  [1885,  PL  LXXXV,  fig.  5;  and  1891.  PL  II,  fig.  4c]. 
2g.  Enlargement  of  the  posterior  portion  of  figure  2f. 
2h.  Front  view  of  the  process  and  platform  shown  in  figure  2g. 

The  specimens  represented  are  all  from  Locality  367a,  Middle  Cambrian,  lower  portion  of  the  "Neobolus  beds" 
in  purplish,  fine-grained,  micaceous  sandstone  at  Jutdna,  Salt  Range,  India. 

DisciNOLEPis  GRANULATA  Waagen  (ji.  664). 

Figure  3.  Exterior  \-iew  of  tlie  typo  specimen,  a  ventral  valve,  from  Locality  367a  Middle  Cambrian,  lower  portion 
of  the  "  Neobolus  beds''  in  purplish,  fine-grained,  micaceous  sandstone  at  Jutdna,  Salt  Range.  India. 
Geol.  Survey  India  Cat.  No.  3/792.  Specimen  figured  by  Waagen  [I8S5.  PL  LXXXVI.  figs,  (ia-b; 
and  1891,  PL  II,  figs.  IGa-b]. 
3a  and  31>.  Rack  and  side  views  of  a  ventral  valve  from  Locality  367c,  Middle  Cambrian,  lower  portion  of  tlie 
"  A'^rofto/»sbeds"inpurpli.sh,  fine-grained,  micaceous  sandstone  near  the  fresh-water  springsina  gorge 
above  the  salt  mines  at  Kiura  (KhewraV  Salt  Range.  India.  Geol.  Survey  India  Cat.  No.  3/791.  The 
triangular  space  shown  in  figure  3a  is  not  filled  in  with  the  shell;  it  is  an  open  slit.  Specimen  figured 
by  Waagen  [1885,  PI.  LXXXVI,  figs.  5a-b;  and  1891.  PL  II,  figs.  15a-b]. 
270 


U.   S.   GEOLOGICAL  SURVEY 


MONOGRAPH   LI     PL.  LXXXI 


FRANCES  WIESER  DEL. 


PLATE  LXXXI.  271 

Keyserlingia  buchi  (de  Verneuil)    (p.  628). 

Figure  4.  Exterior  view  of  a  fragmentary  ventral  valve.     U.  S.  Nat.  Mus.  Cat.  No.  52049a.     (See  figs.  4b  and  4c.) 
4a.  Interior  view  of  the  posterior  portion  of  a  ventral  valve.     U.  S.  Nat.  Mus.  Cat.  No.  52049d. 
4b.  Interior  of  the  posterior  portion  of  the  specimen  represented  by  figure  4. 
4c.  Posterior  view  of  the  specimen  represented  by  figures  4  and  4b. 
4d.  Interior  view  of  the  posterior  portion  of  a  ventral  valve  in  which  the  pedicle  tube  pr(]jeil,s  and  opens  toward 

the  front  of  the  valve.     U.  S.  Nat.  Mus.  Cat.  No.  52049b. 
4d'  and  4d".  Side  and  front  views  of  specimen  represented  by  figure  4d. 
4e.  Interior  of  the  posterior  portion  of  a  dorsal  \-alve.     U.  S.  Nat.  Murj.  Cat.  No.  52049c. 

The  specimens  represented  are  all  from  Locality  9d,  Upper  Cambrian  Obolus  sandstone  at  Jaggowal,  about  20 
miles  (32  km.)  east-southeast  of  Reval,  Government  of  Esthonia,  Russia. 

SiPHONOTRETA    VERRUCOSA    (Eicliwaltl)     (p.  627). 

Figures  5,  5a,  and  5b.  Ventral,  dorsal,  and  side  views  of  a  specimen  having  the  two  valves  united.     U,  S.  Nat.  Mus. 
Cat.  No.  52217a.     From  Locality  337m,  passage  beds  IxHween  the  Upper  Cambrian  and  the  Ordo- 
■  vician,  Orthoceratitc  limestone  at  Popowka,  near  St.  Petersburg,  Russia. 

SiPHONOTRETA    UNGUICULATA    (Eichwal(l)     (}).  626). 

Figures  6  and  6a.  Ventral  and  dor.sal  views  of  a  shell  having  the  two  valves  united,  from  Locality  337m,  passage  beds 

between  the  Upper   Cambrian  and  the  Ordovician,    Orlhoccratite  limestone  at  Popowka,  near  St. 

Petersbui-g,  Russia.  U.  S.  Nat.  Mus.  Cat.  No.  52218a. 
6b.  Side  view  of  the  specimen  represented  by  figures  6  and  6a. 
6c.  Interior  of  posterior  portion  of  ventral  valve,  showing  opening  of  pedicle  tube  and  the  muscle  scars.     Copied 

from  Davidson  [1877,  PI.  II,  fig.  9]. 
6d  and  6e.  Interior  of  dorsal  and  ventral  valves,  respectively.     From  a  ca.st  of  a  natural  mold  of  a  specimen 

which  has  the  two  valves  united  and  which  is  from  the  same  locality  as  the  specimen  represented  by 

figures  G,  6a-b.     U.  S.  Nat.  Mus.  Cat.  No.  52218b. 

SiPHONOTRETA?    DUBIA    Walcott    (p.  62.5). 

Figures  7  and  7a.  Top,  side,  and  posterior  views  of  ventral  valves  from  Locality  Iv,  Lower  Cambrian  shales  of  No.  3 
of  the  Silver  Peak  group  [\\'alcott,  19081,  p.  189],  3  miles  (4.8  km.)  north  of  Valcalda  Spring  and  4 
miles  (6.4  km.)  west-northwest  of  the  Drinkwater  mine.  Silver  Peak  quadrangle  (U.  S.  Geol.  Survey), 
Esmeralda  County,  Nevada.  U.  S.  Nat.  Mus.  Cat.  Nos.  52215a  and  52215b.  Figure  7  represents  the 
type  specimen. 
7b.  Exterior  view  of  a  fragmentary  dorsal  valve  associated  with  the  specimens  represented  by  figures  7  and  7a. 
U.-S.  Nat.  Mus.  Cat.  No.  52215c. 

Orbiculoidea  varians  (Barrande)    (p.  72.3). 

FIGURE  8.  Ventral  valve  from  Locality  303c,  passage  beds  between  the  irpper  Cambrian  and  Ordovician,  suburbs  of 
Hof,  Bavaria,  X  J.     Copied  from  Barrande  [1868a,  fig.  71].     This  is  the  type  specimen. 

Orbiculoidea  contraria  (Barrande)    (p.  722). 

Figure  9.  Ventral  valve  from  Locality  303c,  passage  beds  between  the  Upper  Cambrian  and  the  Ordovician.  suburbs 
o-'  Hof,  Bavaria,  X  J.     Copied  from  Barrande  [1868a,  fig.  72].     This  is  the  type  specimen. 

Philhedra  COLUMBIAN-^  (Walcott)    (p.  724). 

Figures  10  and  10'.  Summit  and  back  views  of  the  t\^)e  specimen.  Locality  14s,  Middle  Cambrian  0<jii(jopsis  zone, 
on  Mount  Stephen,  al)ove  Field,  British  Columbia.  U.  S.  Nat.  Mus.  Cat.  No.  58307.  Copied  from 
Walcott  [1908c,  PI.  I,  figs.  5  and  5a]. 


272  PLATE  LXXXI. 

Orbiculoidea  piLEOLUs  (Hicks  MS.)    (Salter)   (p.  722). 

FioiRE  11.  Exterior  of  ventral  valve,  the  type  specimen,  from  Locality  318d,  Middle  Cambrian,  Menevian  Band- 
stones  at  Porth-y-rhaw,  St.  Davids,  South  Wales.     Copied  from  Davidson  [18G8,  PI.  XVI,  fig.  11a]. 
11a.  Exterior  of  dorsal  valve  from  the  locality  represented  by  figure  11.     Copied  from  Davidson  [1868,  PI. 
XVI,  fig.  12a]. 

ACROTHELE    LEVISENSIS    Walcott     (p.  646). 

Figure  12.  Exterior  of  a  compressed  ventral  valve,  the  type  specimen.     Geol.  Survey  Canada.     Copied  from  Walcott 
[1908d,  PI.  VIII,  fig.  13]. 
12a.  Exterior  of  a  compressed  dorsal  valve.     Geol.  Survey  Canada. 
12b.  Cast  of  the  interior  of  a  dorsal  valve.     Geol.  Survey  Canada. 

The  specimens  represented  are  all  from  Locality  319a,  Lower  Ordo%'ician  Levis  shales  at  Point  Le\ds,  Quebec, 
Canada. 


PLATE   LXXXII. 


62e67°— VOL  51,  PT  2—12 18  273 


PLATE  LXXXII. 

cl.  Cardinal  scar.  F'.  Cast  of  foranilnal  tube. 

F.  Foramen.  vs.  Vascular  sinuses. 

YORKIA    WANNEKI    Walcott  (p.  612). 

Figure  1.  Exterior  of  a  corrugated  ventral  valve,  drawn  from  a  cast  of  a  natural  matrix.     U.  S.  Nat.  Mus.  Cat.  No. 

26433]. 
la.  Exterior  and  side  outline  of  a  smooth  ventral  valve,  drawn  from  a  cast  of  a  natural  matrix.     U.  S.  Nat. 

Mus.  Cat.  No.  26433a.     Specimen  figured  by  Walcott  [1897b,  PI,  LX,  fig.  ]]. 
lb.  Top  view,  back  view,  and  side  outline  of  an  elevated  ventral  valve,  drawn  from  a  cast  of  a  natural  matrix. 

U.  S.  Nat.  Mus.  Cat.  No.  26433b. 
Ic.  Top  and  back  views  of  cast  of  the  interior.    U.  S.  Nat.  Miis.  Cat.  No.  26433c.    Specimen  figured  by  Walcott 

[lS97b,  PI.  LX,  fig.  la]. 
Id.  Exterior  of  a  dor.sal  valve,  drawn  from  a  cast  of  a  natural  matrix.     U.  S.  Nat.  Mus.  Cat.  No.  26433d. 
le.  Cast  of  the  interior  of  the  posterior  portion  of  a  ventral  valve.     U.  S.  Nat.  Mus.  Cat.  No.  26433e. 
If  and  Ig.  Casts  of  the  interiors  of  ventral  valves,  with  side  outlines  of  same.     U.  S.  Nat.  Mus.  Cat.  Nos.  26433f 

and  26433g,  respectively.     The  specimen  represented  by  figure  Ig,  the  type,  was  figured  by  Walcott 

[1897b,  PL  LX,  figs,  lb  and  Ic]. 
Ih.  Cast  of  the  interior  of  a  dorsal  valve.     U.  S.  Nat.  Mus.  Cat.  No.  26433h.     Specimen  figured  by  Walcott 

[1897b,  PI.  LX,  fig.  Id], 
li.  Area  of  dorsal  valve  drawn  from  the  cast  of  a  natural  mold  (original  specimen  missing).     U.  S.  Nat.  Mus. 

Cat.  No.  26433i.     Specimen  figured  by  Walcott  [1897b,  PI.  LX,  fig.  le]. 

The  specimens  represented  are  all  from  Locality  49,  Lower  Cambrian  sandstone  on  Codorus  Creek,  near  Emigsville, 
York  County,  Pennsylvania. 

YoRKIA?    WASHIXGTOXENSIS    Walcott  (p.  613). 

Figure  2.  Cast  of  the  interior  of  a  ventral  valve  from  Locality  37b,  Lower  Cambrian  limestone  0.25  mile  (0.4  km.)  east 
of  Salem,  Washington  County,  New  York.     U.  S.  Nat.  Mus.  Cat.  .No.  26434a.     Type   specimen 
figured  by  Walcott  [1897b,  PI."  LX,  fig.  3]. 
2a.  Cast  of  the  interior  of  a  dorsal  valve  from  Locality  338n,  Lower  Cambrian,  western  belt  of  conglomeratic 
limestone,  Rensselaer  County,  New  York.     V.  S.  Nat.  Mus.  Cat.  No.  52207a. 

YoRKIA  ?    ORIENTALIS    Walcott  (p.  612). 

Figures  3  and  3'.  Top  and  side  views  of  ventral  valve  from  Locality  C71,  Middle  Cambrian  limestone  in  Kichou 
formation  [Willis  and  Blackwelder,  1907,  pp.  139  and  145],  4  miles  (6.4  km.)  southwest  of  Tungytl, 
Shansi,  China.     U.  S.  Nat.  Mus.  Cat.  No.  52521a.     This  is  the  type  specimen. 
3a.  Enlargement  of  the  outer  surface  of  the  specimen  represented  by  figure  3. 

YoRKiA  ?  MiQUELi  AYalcott  (p.  611). 

Figure  4.  Exterior  of  ventral  valve  from  Locality  342a,  Lower  Ordovician?,  barren  f|uartzitic  beds  at  Coulouma, 
Department  of  H6rault,  France.     This  is  the  type  specimen.     Collection  of  J.  Miquel. 

DisciNOPSis  GULiELMi  (Matthew)  (p.  720). 

Figure  5.  A  compressed  ventral  valve.     Type  specimen,  figured  by  Matthew  [1886,  PI.  V,  figs.  14c  and  14dJ. 

5a  and  5b.  Interiors  of  ventral  valves.  Figure  5a  is  drawn  from  the  specimen  figured  by  Hall  and  Clarke 
[1892a,  PI.  Ill,  fig.  21,  and  1892c,  PI.  Ill,  figs.  21  and  22].  Figures  5a  and  5b  are  drawn  from  speci- 
mens among  those  figured  by  Matthew  [1886,  PI.  V,  figs.  14,  14a-b,  and  14e],  but  closer  identification 
is  impossible. 

5c.  Interior  of  a  dorsal  valve.  Specimen  figured  by  Hall  and  Clarke  [18920,  PI.  Ill,  fig.  23].  Its  identifica- 
tion with  any  of  the  figures  given  by  Matthew  [1886,  PI.  V,  figs.  14,  14a-b,  and  14e]  is  impossible. 

The  specimens  represented  are  all  from  Locality  301g,  Middle  Cambrian  sandstones  of  Division  Ic  of  Matthew  at 
Portland,  now  a  part  of  the  city  of  St.  John,  St.  John  County,  New  Brunswick.     They  are  in  the  collection  of  the 
University  of  Toronto,  Canada. 
274 


U.  S.   GEOLOGICAL  SURVEY 


MONOGRAPH    LI     PL.  LXXXK 


FRANCES  WIESER  DEL. 


rt-iOTYPE   CO   BOSTON 


PLATE  LXXXII.  275 

,     DisciNOPsis?  suLCATus  Walcott  (p.  721) . 

Figure  6.  Cast  of  the  interior  of  a  ventral  ?  valve,  the  type  specimen,  from  Locality  C66,  Upper  Cambrian  Chaumitien 
limestone  at  Pagoda  Hill,  1  mile  (1.6  km.)  west  of  Tsinan,  Shantung,  China.  U.  S.  Nat.  Mus.  Cat. 
No.  52522a. 

Dearbornia  clarki  Walcott  (p.  614). 

Figures  7  and  7a.  Exteriors  of  ventral  valves.     U.  S.  Nat.  Mus.  Cat.  Nos.  52214a  and  52214b,  respectively.     Figure 
7,  that  of  the  type  specimen,  is  copied  from  Walcott  [1908d,  PI.  VIII,  fig.  7]. 
7b.  Cast  of  the  interior  of  a  ventral  valve.     U.  S.  Nat.  Mus.  Cat.  No.  52214c. 
7c.  Cast  of  the  interior  of  a  dorsal  valve.     U.  S.  Nat.  Mus.  Cat.  No.  52214d. 
7d.  Exterior  of  a  dorsal  valve.     U.  S.  Nat.  Mus.  Cat.  No.  52214e. 

The  specimens  represented  are  all  from  Locality  9k,  Middle  Cambrian  limestone  forming  Ic  of  the  Dearborn  River 
section  [Walcott,  1908f,  p.  201],  eastern  part  of  the  Lewis  and  Clark  National  Forest,  Montana. 

Trematobolus  excelsis  Walcott  (p.  617). 

Figure  8.  Top  view,  with  outline  of  side  and  back  views,  of  a  cast  of  a  ventral  valve,  the  type  specimen.     U.  S.  Nat. 
Mus.  Cat.  No.  52208a.     Copied  from  Walcott  [1908d,  PI.  VIII,  fig.  8]. 
8a  and  8b.  Top  view,  with  outline  of  side  and  back  views,  of  exteriors  of  ventral  valves.     U.  S.  Nat.  Mus. 
Cat.  Nos.  52208b  and  52208c,  respectively. 

The  specimens  represented  are  all  from  Locality  53,  Lower  Cambrian  sandstones  in  the  lower  portion  of  3d  of  the 
Waucoba  Springs  section  [Walcott,  19081,  pp.  187  and  18S],  1  mile  (l.G  km.)  east  of  Saline  Valley  road  about  2.5  miles 
(4  km.)  east^ortheast  of  Waucoba  Springs,  Inyo  County,  California. 


PLATE   LXXXIII. 


277 


PLATE  LXXXIII. 

cl.  Cardinal  scar.  '  s.  Median  septum. 

F'.  Cast  of  foraminal  tul)e.  v.  Visceral  area. 

h.  Central  muscle  scar.  vs.  Vascular  sinuses. 

j.  Anterior  lateral  muscle  scarL 

Trematobolus  kempanum  (Matthew)  (p.  619). 

Figure  1.  Exterior  of  a  ventral  valve,  showing  elongate  slit  into  which  the  foramen  opens,  drawn  from  a  oast  of  a 

natural  matrix.     U.  S.  Nat.  Mus.  Cat.  No.  52212a. 
la.  A  dorsal  valve  associated  with  the  specimen  repre.sented  by  figure  1,  drawn  from  a  cast  of  a  natural  matrix. 

U.  S.  Nat.  Mus.  Cat.  No.  52212b. 
lb.  A  crushed  ventral  valve  from  Locality  308g,  Middle  (  ambrian  shales  of  Division  lb.3  or  lb4  of  Matthew's 

section  on  Long  Island  [Matthew,  1898a,  pp.  124  and  127],  Kennebecasis  Bay,  St.  John  County, 

New  Brunswick.     LTniversity  of  Toronto,  Canada. 
Ic  and  Id.  Casts  of  the  interiors  of  ventral  valves.     U.  S.  Nat.  Mus.  Cat.  Nos.  52212c  and  52212d,  respectively, 
le.  Cast  showing  cast  of  the  foraminal  tube;  the  dark  portion  represents  the  thickness  of  the  shell.     U.  S. 

Nat.  Mus.  Cat.  No.  52212e. 
It.  Cast  of  the  interior  of  a  dorsal  valve.     U.  S.  Nat.  Mus.  Cat.  No.  52212f. 

Ig.  Natural  cast  of  the  interior  of  a  ventral  valve.     U.  S.  Nat.  Mus.  Cat.  No.  52212g.     (See  fig.  Ij.) 
Ih.  Fragment  showing  the  thickened  shell  on  the  posterior  jiortion  of  a  shell  associated  with  the  specimen 

represented  by  figure  lb.     LTniversity  of  Toronto,  Canada. 
li.  Cast  of  the  interior  of  a  ventral  valve.     U.  S.  Nat.  Mus.  Cat.  No.  52212h. 
Ij.  Interior  of  a  ventral  valve  drawn  from  a  cast  of  the  specimen  represented  by  figure  Ig.     U.  S.  Nat.  Mus. 

Cat.  No.  52212i. 
Ik.  Enlarged  view  of  a  cast  of  the  interior  of  a  ventral  valve.     U.  S.  Nat.  Mus.  Cat.  No.  52212J. 
1 1.  Partly  exfoliated  dorsal  valve.     U.  S.  Nat.  Mus.  Cat.  No.  52212k. 
Im.  Cast  of  the  interior  of  a  dorsal  valve.     U.  S.  Nat.  Mus.  Cat.  No.  52212  1. 

In.  Interior  of  a  broken  ventral  valve  drawn  from  a  cast  of  a  natural  mold.     U.  S.  Nat.  Mus.  Cat.  No.  52212m. 
lo.  Fragment  of  the  interior  of  a  dorsal  valve,  showing  the  peculiar  median  septum.     U.  S.  Nat.  Mus.  Cat. 

No.  52212n. 

With  the  exception  of  figures  lb  and  Ih,  all  of  the  specimens  represented  are  from  Locality  2u,  Middle  Cambrian, 
lowest  beds  exposed  on  the  south  side  of  Long  Lsland  [Matthew,  1898a,  pp.  124  and  127],  Kennebecasis  Bay,  St.  John 
County,  New  Brunswick. 

Trematobolus  pristinus  (Mattliew)  (p.  621). 

[PI.  L.\.\.\IV,  fig.  6.] 

FiQUEE  2.  Exterior  of  a  ventral  valve  from  Locality  21,  Middle  Cambrian  sandstones  of  Division  lb3  of  Matthew  on 
Hanford  Brook,  St.  John  County,  New  Brunswick.     U.  S.  Nat.  Mus.  Cat.  No.  52213a. 

2a.  Interior  of  a  ventral  valve  associated  with  the  specimen  represented  by  figure  2.  U.  S.  Nat.  Mus.  Cat. 
No.  .52213b. 

2b.  Interior  of  a  ventral  valve  associated  with  the  specimen  represented  by  figure  2.  U.  S.  Nat.  Mus.  Cat. 
No.  52213c. 

2c.  Natural  cast  of  the  interior  of  the  ventral  valve  represented  by  figure  2b.     U.  S.  Nat.  Mus.  Cat.  No.  52213d. 

The  specimens  represented  by  figures  2b  and  2c  are  counterparts;  another  specimen  (Cat.  No.  56955b,  from  Locality 
2h)  was  used  in  drawing  both  figures. 

FiQURE  2d.  Cast  of  the  interior  of  a  dorsal  valve  from  Locality  2h,  Middle  I  ambrian  sandstones  of  Division  lb2  of 

Matthew  on  Hanford  Brook,  St.  John  County,  New  Brunswick.     U.  S.  Nat.  Mus.  Cat.  No.  56955a. 
2o.  Exterior  andside  views  of  a  dorsal  valve  from  Locality  301,  Middle  Cambrian  sandstones  of  Division  lb2 

of  Matthew  on  Hanford  Brook,  St.  John  County,  New  Brunswick.     Original  in  the  collection  of  the 

University  of  Toronto,  Canada;  cast  in  the  United  States  National  Museum  (Cat.  No.  58308). 
2f.  Cast  of  the  interior  and  side  view  of  dorsal  valve  as-sociated  with  the  specimen  represented  by  figure  2e. 

University  of  Toronto,  Canada.     Type  specimen,  figured  by  Matthew  [isn5a,  PI.  IV,  fig.  Ic]  as  Obolus 

pristinus. 
2g.  Cast  of  the  interior  of  a  dorsal  valve  associated  with  the  specimen  represented  by  figure  2e.     University 

of  Toronto,  Canada. 
2h.  Broken  cast  of  interior  of  dorsal  valve,  with  side  outline,  associated  with  the  specimen  represented  by 

figure  2e.     University  of  Toronto,  Canada. 
278 


U.  S.   GEOLOGICAL  SURVEY 


MONOGRAPH   LI     PL.LXXXIII 


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tPC   COBCSTON 


PLATE    luXJOny 


279 


PLATE  LXXXIV. 


F.  Foramen. 

F'.  Cast  otforaminnl  tube, 
g.  Umbonal  muscle  scars. 
h.  Central  muscle  scar, 
i.  Transmedian  muscle  scar, 
j.  Anterior  lateral  muscle  scar. 


p.  Cast  of  false  pedicle  furrow, 
pf.  Underside  of  pedicle  furrow. 

s.  Median  septum. 

t.  Teeth, 
vs.  Vascular  sinus. 


SCHIZAMBON    TYPICALIS    Walcott   (p.  624). 

Figure  1.  Exterior  of  ventral  valve.     U.  S.  Nat.  Mus.  Cat.  No.  24556a. 

la.  Interior  of  ventral  valve,  the  type  specimen.     U.  S.  Nat.  Mus.  Cat.  No.  24556b. 

lb.  Exterior  of  dorsal  valve.     U.  S.  Nat.  Mus.  Cat.  No.  24556c. 

Ic.  Interior  of  dorsal  valve.     TJ.  S.  Nat.  Mus.  Cat.  No.  24556d. 

Id.  A  portion  of  the  surface  enlarged  to  show  the  minute  surface  spines.     U.  S.  Nat.  Mus.  Cat.  No.  24556e. 

The  specimens  represented  are  all  from  Locality  201a,  Lower  Ordovician  Pogonip  limestone  on  east  slope  of  ridge 
east  of  Hamburg  Ridge,  Eureka  district,  Nevada.  The  figiu-es  (1,  la-d)  are  copied  from  Walcott  [1884b,  PL  I, 
figs.  3a,  3,  3c,  3b,  and  3d.  respectively]. 

ScHiZAMBON  PRiscus  Matthcw  (p.  623). 

Figures  2  and  2'.  Exterior  and  side  views  of  ventral  valve  from  Locality  3q,  Upper  Cambrian  shale  in  Barachois  Glen, 

4  miles  (6.4  km. )  south  of  Little  Bras  d'Or  Lake,  Cape  Breton,  Nova  Scotia.     U.  S.  Nat.  Mus.  Cat.  No. 

52226a. 
2a.  Exterior  of  ventral  valve  associated  with  the  specimen  represented  by  figure  2. 

52226b. 
2b.  Interior  of  ventral  valve  associated  with  the  specimen  represented  by  figure  2. 

52226c. 
2c.  Interior  of  a  broken  dorsal  valve  from  Locality  101,  Upper  Cambrian  shale  on  east  bank  of  Barachois  River, 

6  miles  (9.6  km.)  from  Little  Bras  d'Or  Lake,  Cape  Breton,  Nova  Scotia.     U.  S.  Nat.  Mus.  Cat.  No. 

52227a. 
2d.  Interior  of  a  dorsal  valve  associated  with  the  specimen  represented  by  figure  2c. 

52227b. 
2e.  Interior  of  a  dorsal  valve  associated  with  the  specimen  represented  by  figure  2. 

52226d. 


U.  S.  Nat.  Mus.  Cat.  No. 
U.  S.  Nat.  Mus.  Cat.  No. 


U.  S.  Nat.  Mus.  Cat.  No. 
U.  S.  Nat.  Mus.  Cat.  No. 


SCHIZAMBON    MANITOUENSIS    Walcott   (p.  623). 

Figure  3.  Exterior  of  a  ventral  valve,  the  type  specimen.     U.  S.  Nat.  Mus.  Cat.  No.  52224a. 
3a.  Exterior  of  a  dorsal  valve.     U.  S.  Nat.  Mus.  Cat.  No.  52224b. 
3b.  Cast  of  interior  of  a  dorsal  valve.     U.  S.  Nat.  Mus.  Cat.  No.  52224c. 
3c.  Interior  of  a  dorsal  valve.     U.  S.  Nat.  Mus.  Cat.  No.  52224d. 

3d.  Outline  of  posterior  portion  of  cast  of  the  interior  of  a  ventral  valve.     U.  S.  Nat.  Miuj.  Cat.  No.  52224e. 
3e.  Outline  of  posterior  portion  of  interior  of  a  ventral  valve.     U.  S.  Nat.  Mus.  Cat.  No.  52224f. 

The  specimens  represented  by  figures  3,  3a-c  are  from  Locality  186a,  and  those  represented  by  figures  3d  and  3e 
from  Locality  186,  a  slightly  lower  horizon;  both  near  the  line  between  the  red  and  gray  Ordovician  limestone  in  red 
limestone  of  Lower  Ordovician  age,  Williams  Canyon,  Manitou,  El  Paso  County,  Colorado. 

SCHIZAMBON?    ESTHONIA    Walcott   (p.  622). 

Figures  4  and  4'.  Exterior  and  side  view  of  the  type  specimen,  a  ventral  valve,  from  Locality  336h,  Upper  Cambrian 
Ungulite  grit,  at  Baltischport,  Esthonia,  Russia.     U.  S.  Nat.  Mus.  Cat.  No.  52222a. 
280 


U.  S.   GEOLOGICAL   SURVEY 


MONOGRAPH   Li     PL.  LXXXIV 


FRANCES  W1ESER  DEL. 


M-Liorvpe   CO  aosrox 


PLATE  LXXXIV.  281 

Trematobolus  iNSiGNis  Mattliew  (p.  617). 

Figure  5.   Natural  cast,  of  the  interior  of  a  ventral  valve.     UniverBity  of  Toronto,  Canada.    Type  specimen,  figured 

by  Matthew  [1893a,  (ig.  lb,  p.  270],     (See  fig.  5a.) 
5a.  Cast  taken  from  the  natural  mold  of  the  interior  of  the  ventral  valve  represented  by  figure  5.     U.  S.  Nat. 

Mus.  Cat.  No.  52211a. 
5b.  Interior  of  a  ventral  valve.    University  of  Toronto,  Canada.     Specimen  figured  by  Matthew  [189.3a,  fig.  la, 

p.  276].     (See  fig.  5c.) 
5c  and  5c'.  Top  and  back  views  of  an  artificial  cast  of  the  interior  of  the  ventral  valve  represented  by  figure  5b. 

U.  S.  Nat.  Mus.  Cat.  No.  52211b. 

The  two  specimens  represented  are  both  from  Locality  301,  Middle  Cambrian  sandstones  of  Division  lb2  of  Matthew 
[1895a,  p.  108],  on  Hanford  Brook,  St.  John  County,  New  Brunswick. 

Trematobolus  pristinus  (Matthew)  (p.  621). 

[PI.  LXXXIII,  figs.  2,  2a-h.I 

Figure  6.  Reproduction  of  a  small  block  of  rock  showing  numerous  specimens.  Locality  2i,  Middle  Cambrian  sand- 
stones of  Division  lb3  of  Matthew  [1895a,  p.  108],  on  Hanford  Brook,  St.  John  County,  New  Brunswick. 
U.  S.  Nat.  Mus.  Cat.  No.  52213f. 


PLATE    LXXXV. 


283 


PLATE  LXXXV. 


a.  Cardinal  area. 

a'.  Anterior  a<lduclor  impressions. 

b.  Dental  sockets. 

c.  Crura. 

d.  Deltidium. 


d'.  Cast  of  umbonal  cavity. 

j.  Cardinal  process, 

0.  Ovarian  spaces. 

r.  Visceral  area. 

t.  Teeth, 
vs.  Vascular  sinus. 


BiLLINGSELLA    COLORADOENSIS    (SllUlUard)    (p.  751). 

[Text  figs.  5,  p.  299,  and  CO,  p.  751.] 

Figure  1.  Exterior  of  typical  form  of  ventral  valve,  from  Locality  70,  Upper  Cambrian  limestone  on  Morgans  Creek, 
Burnet  County,  Texas.  U.  S.  Nat.  Mus.  Cat.  No.  34777b.  The  surface  of  this  specimen  is  enlarged 
in  figure  Ik.     It  is  not  the  type  specimen. 

la.  Exterior  of  a  silicified  ventral  valve,  from  Locality  302g,  Upper  Cambrian  limestone,  north  slope  of  Crow- 
foot Ridge,  Yellowstone  National  Park,  Wyoming.  U.  S.  Nat.  Mus.  Cat.  No.  35213a.  Copied  from 
Walcott  [1899,  PI.  LXI,  fig.  1]. 

lb.  Ventral  valve,  from  Locality  5a,  Upper  Cambrian  limestone  of  the  St.  Charles  formation,  2  miles  southeast 
of  Malade,  Oneida  County,  Idaho.  The  radiating  striae  and  concentric  ridges  of  growth  are  very 
strongly  marked  on  this  specimen.  Other  specimens  show  the  surface  characters  of  figures  1  and  le. 
U.  S.  Nat.  Mus.  Cat.  No.  51403a. 

Ic.  Partly  exfoliated  ventral  valve  from  Locality  68,  Upper  Cambrian  limestone,  Packsaddle  Mountain, 
Llano  County,  Texas.     U.  S.  Nat.  Mus.'  Cat.  No.  34774a. 

Id.  Ventral  valve  from  Locality  97,  Upper  Cambrian  "St.  Croix  .sandstone, "  Reads  Landing,  Wabasha  County, 
Minnesota.     U.  S.  Nat.  Mus.  Cat.  No.  34771a. 

le.  Dorsal  valve  associated  with  the  specimen  represented  by  figure  1.     U.  S.  Nat.  Mus.  Cat.  No.  34777c. 

If.  Dorsal  valve  associated  with  specimen  represented  by  figure  1.     U.  S.  Nat.  Mus.  Cat.  No.  34777d. 

Ig.  Dorsal  valve  associated  with  specimen  represented  by  figure  la.  L^.  S.  Nat.  Mus.  Cat.  No.  35213b.  Copied 
from  Walcott  [1899,  PI.  LXI,  fig.  la]. 

Ih.  Dorsal  valve  associated  with  the  ventral  valve  represented  by  figure  Id.     U.  S.  Nat.  Mus.  Cat.  No.  34771b. 

li.  Dorsal  valve  with  strongly  marked  radiating  cost®,  associated  with  the  specimen  represented  by  figure  Ic. 
U.  S.  Nat.  Mus.  Cat.  No.  34774b. 

Ij.  Small  dorsal  valve  showing  deep  mesial  sinus.  Locality  131,  Upper  Cambrian  "St.  Croix  sandstone,"  4 
miles  east  of  Lake  City,  Wabasha  County,  Minnesota.     U.  S.  Nat.  Mus.  Cat.  No.  34770a. 

Ik.  Enlargement  of  the  surface  of  the  specimen  represented  by  figure  1. 

1  1.  Group  of  silicified  shells  associated  with  the  specimen  represented  by  figure  la.  U.S.  Nat.  Mus.  Cat. 
No.  35213c. 

Im.  Interior  cast  of  ventral  valve,  showing  marked  vascular  .sinuses,  and  a  ridge  corresponding  to  a  median 
groove.     Same  locality  as  specimen  represented  by  figure  Id.     V.  S.  Nat.  Mus.  Cat.  No.  .34771c. 

In.  Impression  of  interior  of  ventral  valve  probably  associa»ted  with  the  specimen  represented  by  figure  Id. 
U.  S.  Nat.  Mus.  Cat.  No.  34771e.  Drawn  from  an  artificial  cast,  the  original  mold  of  which  can  not 
be  located.  The  cast,  with  another  (Cat.  No.  34771f)  which  was  used  to  restore  portions  of  figure  In, 
was  in  a  tray  with  specimens  from  Locality  97,  but  it  may  not  belong  there.     (See  fig.  lu.) 

lo.  Interior  of  ventral  valve  associated  with  the  specimen  represented  by  figure  la.  U.  S.  Nat.  Mus.  Cat.  No. 
35213d.     Copied  from  Walcott  [1899,  PI.  LXI,  fig.  Ic]. 

Ip,  Iq,  and  Ir.  Casts  of  interiors  of  ventral  valves  from  Locality  83%  I'pper  Cambrian  greensand  horizon  in 
"St.  CroLx  sandstone,"  Trempealeau,  Trempealeau  County,  Wiscon.sin.  These  three  figures  repre- 
sent unusually  convex  specimens  that  may  belong  to  a  distinct  species.  U.  S.  Nat.  Mus.  Cat.  Nos. 
52235a,  52235b,  and  52235c,  respectively. 

Is.  Cast  of  the  posterior  portion  of  a  ventral  valve,  with  side  outline.  Locality  70a,  Upper  Cambrian  lime- 
stone, Morgans  Creek,  Burnet  County,  Texas.     U.S.  Nat.  Mus.  Cat.  No.  34777e. 

It.  Cast  of  the  interior  of  a  ventral  valve,  associated  with  specimen  represented  by  figure  la.     U.  S.  Nat.  Mus. 
Cat.  No.  35213e.     Copied  with  slight  alterations  from  the  figure  given  by  Walcott  [1899,  PI.  LXI, 
fig.  Id]. 
284 


U.   S.   GEOLOGICAL  SURVEY 


MONOGRAPH   LI     PL.  LXXXV 


FRANCES  W1ESER  DEL. 


MELIOTVPC    CO    BOSTON 


PLATE  LXXXV.  ,  285 

BiLLiNGSELLA  coLORADOENSis  (Sliumard) — Continued. 

Figure  lu.  Interior  of  dorsal  valve  from  impression  taken  from  natural  cast,  with  outline  of  posterior  view.  Trobably 
from  Locality  97,  Upper  Cambrian  "St.  Croix  sandstone,"  Reads  Landing,  Wabasha  County,  Minne- 
sota. U.  S.  Nat.  Mus.  Cat.  No.  34771g.  Drawn  from  an  artificial  cast,  the  original  mold  of  which  can 
not  be  located.  The  cast  was  in  a  tray  with  specimens  from  Locality  97,  but  it  may  not  belong 
there.     (See  note  under  figure  In.) 

Iv.  Interior  of  dorsal  valve  associated  with  the  specimen  represented  by  figure  Ic.     U.S.Nat  Mus  Cat   No 

34774c. 
Iw.  Interior  of  dorsal  valve  associated  with  the  specimen  represented  by  figure  la.     U.  S.  Nat.  Mus.  Cat.  No. 

35213f.     Copied  with  slight  alterations  from  the  figure  given  by  Walcott  [1899,  PI,  LXI,  fig.  lb]. 
Ix.  Cast  of  the  interior  of  dorsal  valve,  with  side  and  posterior  outlines.     U.  S.  Nat.  Mus.  Cat.  No.  51403b. 

From  Locality  5a.     (See  fig.  lb.) 
ly.  Cast  of  dorsal  valve  associated  with  the  specimen  represented  by  figure  Id.     U.  S    Nat   Mus    Cat    No 

34771d. 
Iz.  Cast  of  posterior  portion  of  interior  of  dorsal  valve  from  Locality  5b,  Middle  Cambrian  Langston  limestone, 

2  miles  (3.2  km.)  southeast  of  Malade,  Oneida  County,  Idaho.     U.  S.  Nat.  Mus.  Cat.  No.  34776a. 


PLATE   LXXXVI. 


287 


PLATE  LXXXVI. 

a.  Cardinal  area.  d".  Umbonal  cavity. 

b.  Dental  sockets.  j.  Cardinal  process. 

c.  Crura.  o.  Ovarian  areas, 
d'.  Cast  of  umbonal  cavity.  vs.  Vascular  sinus. 

BiLLINGSELLA    MAJOR    Walcott    (p.  758). 

Figure  1.  Portion  of  ventral  valve,  showing  cast  of  cardinal  area  and  surface  costse.    Locality  116,  Upper  Cambrian 
sandstone  on  Wells  farm,  2  miles  (3.2  km.)  west  of  Baraboo,  Sauk  Cotmty,  Wisconsin.     U.  S.  Nat. 
Mus.  Cat.  No.  52256a. 
la.  Cast  of  compressed  dorsal  valve,  the  type  specimen,  associated  with  the  specimen  represented  by  figure  1. 
U.  S.  Nat.  Mus.  Cat.  No.  52256b. 

Figures  1  and  la  are  copied  from  Walcott  [1908d,  PI.  X,  figs.  1  and  la]. 

BiLLINGSELLA    ORIENT ALIS    (Whitfield)    (p.  759). 

Figure  2.  Type  specimen,  compressed  in  shale.     Locality  319g,  Lower  Cambrian  shales  in  Parker's  quarry,  near 

Georgia,  Franklin  County,    Vermont.     Copied  from   Whitfield   [1884,  PI.   XIV,  fig.  6]  where  it  is 

figured  as  Orthisina  orientalu. 

2a  and  2b.  Ventral  and  dorsal  valves,  from  Locality  25a,  Lower  Cambrian  limestone  2  miles  (3.2  km.)  east  of 

Swanton,  Franklin  County,  Vermont.     U.  S.  Nat.  Mus.  Cat.  Nos.  52262a  and  52262b,  respectively. 

BiLLINGSELLA    PLICATELLA    Walcott   (p.  759). 
[Text  Hg.  1,  p.  299.) 

Figure  3.  Exterior  and  side  \-iews  of  a  ventral  \alvc  with  rather  strongly  marked  fasciculate  costse.     U.  S.  Nat. 

Mus.  Cat.  No.  52263a. 
3a.  Exterior  and  side  \-iew3  of  ventral  valve  with  strong  costse.     U.  S.  Nat.  Mus.  Cat.  No.  52263b. 
3b.  Exterior  view  of  ventral  valve  on   which  the   surface  has  been  partly  smoothed  by  attrition.     U.  S. 

Nat.  Mus.  Cat.  No.  52263c. 
3c.  Exterior  and  side  views  of  a  very  convex  ventral  valve,  marked  by  very  fine  radiating  striae  and  faint 

costa.     U.  S.  Nat.  Mus.  Cat.  No.  52263d. 
3d.  Exterior  of  a  small,  strongly  costate  ventral  valve  from  Locality  161,  Upper  Cambrian  limestone  in  pixnt 

overlooking  Churn  Canyon,  west  side  of  the  Bridger  Range,  Gallatin  Coimty,  Montana.     U.  S.  Nat. 

Mus.  Cat.  No.  52265a. 
3e.  Exterior  of  a  small,  strongly  costate  dorsal  valve.     U.  S.  Nat.  Mus.  Cat.  No.  52263e. 
3f.  Exterior  of  ventral  valve,  partly  smoothed  by  attrition.     U.  S.  Nat.  Mus.  Cat.  No.  52263f. 
3g.  Partly  exfoliated  ventral  valve.     U.  S.  Nat.  Mus.  Cat.  No.  52263g. 

3h.  Exterior  and  side  view  of  dorsal  valve  smoothed  by  attrition.     U.  S.  Nat.  Mus.  Cat.  No.  52263h. 
3i.  Cast  of  interior  of  ventral  valve,  the  type  specimen,  showing  cardinal  area,  a;  cast  of  va.scuhir  sinus,  vs; 

and  ovarian  areas,  o.     U.  S.  Nat.  Mus.  Cat.  No.  522631. 
3j.  Cast  of  interior  and  side  outline  of  a  transverse  ventral  valve.     U.  S.  Nat.  Mus.  Cat.  No.  52263J. 
3k.  Cast  of  interior  and  side  outline  of  ventral  valve,  on  which  the  vascular  and  other  impressions  are  strongly 

marked.     U.  S.  Nat.  Mus.  Cat.  No.  .52263k. 
3  1.  Cast  of  the  interior  of  dorsal  valve.     U.  S.  Na(.  Mus.  Cat.  No.  52263  1. 
3m  and  3u.  Interiors  of  small,  strongly  marked  ventral  and  dorsal  valves  from  Locality  4j,  Middle  Cambrian 

limestones  at  the  head  of  Deep  Creek,  Canyon  ([uadrangle  (l^  S.  Geol.  Survey),  Yellowstone  National 

Park,  Wyoming.     U.  S.  Nat.  Mus.  Cat.  Nos.  52266a  and  52266b,  respectively. 

With  the  exception  of  figures  3d,  3m,  and  3n,  all  of  the  specimens  represented  are  from  Locality  158,  Upper 
Cambrian  limestone  north  of   East  Gallatin  River,  near  Hillsdale,  Threeforks  quadrangle  (U.  S.  Geol.  Survey), 
Gallatin  County,  Montana. 
288 


U.   S.  GEOLOGICAL  SURVEY 


MONOGRAPH   LI     PL.    LXXXVl 


•«  i  i  "-.Vi'i 


'-itm 


/^'i 


■.^^ 


/ 


"^  '^ 


PRANCES  WIE3ER  DEL. 


MCLIOTVPE    CO    BOSTON 


PLATE  LXXXVI.  289 

BiLLINGSELLA    STRIATA    Walcott   (p.  764). 

Figure  4.  Exterior  of  ventral  valve,  the  type  specimen.     U.  S.  Nat.  Mu.s.  Cat.  No.  52279a. 
4a.  Partly  exfoliated  ventral  valve.     U.  S.  Nat.  Mus.  Cat.  No.  52279b. 
4b.  Cast  of  interior  of  ventral  valve  and  side  outline.     U.  S.  Nat.  Mus.  Cat.  No.  52279c. 
4c.  Cast  of  imperfect  dorsal  valve.     U.  S.  Nat.  Mus.  Cat.  No.  52279d. 

The  specimens  represented  are  all  from  Locality  149a,  Middle  Cambrian  limestone  at  the  forks  of  Polo  Creek, 
above  Cherry  Creek  Basin,  Threeforks  quadrangle  (U.  S.  Geol.  Survey),  Madison  County,  Montana. 

BiLLINGSELLA    WHITFIELDI    (Walcott)    (p.  764). 

Figure  5.  Exterior  of  ventral  valve,  with  outline  restored,  from  Locality  65,  Middle  Cambrian  Eldorado  limestone 
[Walcott,  1908f,  p.  184],  east  slope  of  Prospect  Mountain,  in  New  York  Canyon,  Eureka  district, 
Nevada.     U.  S.  Nat.  Mus.  Cat.  No.  24591a. 
5a.  Exterior  of  dorsal  valve  from  Locality  55b,  Middle  Cambrian  Eldorado  limestone,  west  side  of  Secret 
Canyon,  Eureka  district,  Nevada.     V.  S.  Nat.  Mus.  Cat.  No.  57041a.    This  is  the  type  specimen. 

The  figures  (5  and  5a)  are  redrawn  from  the  specimens  illustrated  by  Walcott  [1884b,  PI.  IX,  figs.  4,  4a-b]. 

BiLLINGSELLA    OBSCURA    Walcott    (]).    758). 

Figure  6.  Exterior  of  an  imperfect  dorsal  valve  from  Locality  74,  Middle  Cambrian  .sandstone  about  .300  feet  (91.4  m. 
above  the  base  of  the  Tonto  group  at  the  head  of  Nunkoweap  Valley,  Grand  Canyon  of  the  Colo- 
rado, Arizona.     U.  S.  Nat.  Mus.  Cat.  No.  52258a.     This  is  the  type  specimen. 

62667°— VOL  52,  pt  2—12 19 


PLATE   LXXXVII. 


291 


PLATE  LXXXVII. 

WiMANELLA?    ANOMAI.A     (Walc.ott)     (p.   745). 

Figure  1.  Exterior  of  a  compressed  ventral  valve,  the  type  specimen.     U.  S.  Nat.  Mw.'^.  Cat.  No.  55223a. 
la.  Impression  in  shale  of  imperfect,  compressed  ventral  valve.     U.  S.  Nat.  Mus.  Cat.  No.  55223b. 
lb.  Area  and  posterior  portion  of  imperfect,  compressed  ventral  valve.    V.  S.  Nat.  Mus.  Cat.  No.  55223c. 
Ic.  Interior  of  distorted  dorsal  valve.     U.  S.  Nat.  Mus.  Cat.  No.  55223d. 
Id.  Impression  in  shale  of  distorted  dorsal  valve.    V.  S.  Nat.  Mus.  Cat.  No.  55223e. 
le.  Exterior  of  dorsal  valve  doubtfully  referred  to  this  species.     U.  S.  Nat.  Mus.  Cat.  No.  55223f. 

The  specimens  represented  are  all  from  Locality  90,  Middle  Cambrian  Conasauga  shale  on  Edwards  farm,  near 
Craigs  Mountain,  about  10  miles  (Ki  km.)  southeast  of  Center,  Cherokee  County,  Alabama. 

BiLLINGSELLA  ?  APPALACHIA  Walcott   (p.  750). 

Figure  2.  Compressed  and  distorted  ventral  valve.     U.  S.  Nat.  Mus.  Cat.  No.  57073a. 

2a.  Compressed  ventral  valve,  the  type  specimen,  preser\-ing  surface  costae.    U.S.  Nat.  Mus.  Cat.  No.  57073b. 
2b.  Impression  in  shale  of  compressed  dorsal  valve.     U.  S.  Nat.  Mus.  Cat.  No.  57073c. 

The  specimens  represented  are  all  from  Locality  121,  Middle  Cambrian  Rogers^^lle  shale,  road  just  east  of  Harlan 
Knob,  4  miles  (6.4  km.)  northeast  of  Rogersville,  Hawkins  County,  Tennessee. 

BiLLINGSELLA    SALEMENSIS    (Walcott)    (p.  763). 

FiGUUE  3.  Exterior  view  of  the  type  specimen,  a  \entral  valve,  with  side  outline.    The  slope  of  the  cardinal  area  is 
drawn  in  from  the  position  of  the  beak  and  the  cardinal  angle.     U.  S.  Nat.  Mus.  Cat.  No.  17443a. 
3a.  Exterior  of  an  imperfect  dorsal  valve.     U.  S.  Nat.  Mus.  Cat.  No.  17443b. 

The  specimens  represented  by  figures  3  and  3a  are  from  Locality  36,  Lower  Cambrian  limestone,  1  mile  (1 .6  km.) 
south  of  Shushan  and  3.5  miles  (5.6  km.)  north-northeast  of  Cambridge,  \\ashington  County,  New  York.  The  figures 
(3  and  3a)  are  redrawn  from  the  specimens  illustrated  by  Walcott  [1887,  PI.  I,  figs.  17  and  17a,  respectively]. 

BiLLINGSELLA    HIGHLANDENSIS    (VV'^alcott)    (p.  756). 

Figure  4.  Exterior  of  imperfect  ventral  valve.     U.  S.  Nat.  Mus.  Cat.  No.  15355a.     Specimen  figured  by  Walcott 
[188eb,  PI.  VIII,  fig.  3b]. 
4a.  Interior  cast  of  ventral  valve,  the  outline  of  which  has  been  restored  from  another  specimen  (Cat.  No. 

1535oe).     U.  S.  Nat.  Mus.  Cat.  No.  1535.5b. 
4b.  Interior  cast  of  a  ventral  valve  with  deep  furrows  that  represent  the  ridges  of  the  main  vascular  trunks 
and  the  median  ridge  at  the  bottom  of  the  delthyrium.     The  cast  of  the  dental  plates  is  also  clearly 
shown.     U.  S.  Nat.  Mus.  Cat.  No.  15355c.    Type  specimen  figured  by  Walcott  [ISSGb,  PI.  VIll,  fig.  3a]. 
4c.  Imperfect  cast  of  the  interior  of  a  dorsal  valve.     IT.  S.  Nat.  Mus.  Cat.  No.  15355d.     Specimen  figured  by 
Walcott  [1886b,  PI.  VIII,  fig.  3]. 
The  specimens  represented  are  all  from  Locality  31a,  Lower  Cambrian  limestone  in  Pioche  formation  near  Pioche, 
Lincoln  County,  Nevada. 

WiMANELLA    HAULAXENSIS    (Walcott)    (p.   746). 

Figure  5.  Exterior  of  imperfect  ventral  valve.     U.  S.  Nat.  Mus.  Cat.  No.  52252a.     Another  specimen  (Cat.  No. 

52252b)  was  used  in  drawing  certain  portions  of  this  figure. 
5a.  Exterior  of  dorsal  valve.     U.  S.  Nat.  Mus.  Cat.  No.  52252c. 
5b.  Cast  of  interior  of  ventral  valve,  the  type  specimen,  associated  on  same  hand  specimen  with  figure  5a. 

U.  S.  Nat.  Mus.  Cat.  No.  52252d. 
5c.  Partial  cast  of  interior  ot  ventral  valve.     V.  S.  Nat,  Mus.  Cat.  No.  52252e. 
5d.  Caat  of  interior  of  a  beautifully  preserved  portion  of  an  abnormal  dorsal  valve.     U.  S.  Nat.  Mus.  Cat. 

No.  52252f.     Another  specimen  (Cat.  No.  522.52g)  was  used  in  drawing  certain  portions  of  this  figure. 

The  specimens  represented  are  all  from  Locality  121,  Middle  Cambrian  Rogersville  shale,  road  just  east  of  Harlan 
Knob,  4  miles  (G.4  km.)  northeast  of  Rogersville,  Hawkins  County,  Tennessee. 
292 


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MONOGRAPH   LI     PL.  LXXXVH 


FRANCES  WIESER  DEL. 


MELIOTypE   CO   BOSTON 


PLATE  LXXXVII.  293 

BiLLiNGSKLLA  LiNDSTROMi  (Linnarsson)  (p.  757). 

Figure  6.  Exterior  and  side  views  of  nearly  entire  ventral  valve  from  Locality  320n,  Middle  ("ambrian  limestones  of 
the  Paradojcides  forchhammeri  zone  at  Lovened,  Djupadal,  19  miles  (30.6  km.)  south-southeast  of 
Skara,  Province  of  Skaraborf;,  Sweden.     U.  S.  Nat.  Mus.  Cat.  No.  52260a. 

6a  and  6b.  Exterior  views  of  ventral  and  dorsal  valves  with  coarse  costEe.  U.  S.  Nat.  Mus.  Cat.  Nob.  52259a 
and  .522.59b,  respectively. 

6c  and  6d.  Exterior  and  side  views  of  dorsal  valves.  U.  S.  Nat.  Mus.  Cat.  Nos.  522.59c  and  52259d,  respec- 
tively. 

6e.  Cast  of  the  interior  of  a  ventral  valve.     U.  S.  Nat.  Mus.  Cat.  No.  52259e. 

6f.  Cast  of  the  interior  of  a  dor,sal  valve.  U.  S.  Nat.  Mus.  Cat.  No.  .522.59f.  The  beak  is  added  from  another 
specimen  (Cat.  No.  52259g). 

The    specimens  represented  by  figures  6a-f  are  all   from   Locality  320q,  Middle  Cambrian  limestones  of   the 
Paradoxides forchhamtneri  zone  at  Alunbruk  (alum  works),  southern  part  of  Oelaiid  I.sland,  Sweden. 

WiMANELLA    SAFFORDI    (Walcott)    (p.  747). 

Figure  7.  Cast  of  interior  of  a  ventral  valve,  the  type  specimen.     U.  S.  Nat.  Mus.  Cat.  No.  52268a. 
7a.  Cast  of  interior  of  a  dorsal  valve.     U.  S.  Nat.  Mus.  Cat.  No.  52268b. 
The  specimens  represented  are  both  from  Locality  14a,  Middle  Cambrian  sandstone  of  the  Rome  formation  along 
First  Creek  Gap,  4  miles  (6.4  km.)  north-northeast  of  Knoxville  [Keith  1905,  areal  geology  sheet],  Knox  County, 
Tennessee. 


PLATE   LXXXVIII. 


295 


PLATE  LXXXVIII. 

a'.  Anterior  adductor  impressions.  <i'.  Cast  of  umbonal  cavify. 
a".  Posterior  adductor  impressions.  j.  Cardinal  process. 

c.  Crura.  s.  Median  septum, 

cp.  Septal  plates. 

BiLLiNGSELL.\  EXPORRECTA  (Liiuiarsson )  (p.  754). 

Figure  1.  Exterior  and  side  views  of  a  ventral  valve  preserving  the  outer  .surface.     U.  S.  Nat.  Mus.  Cat.  Xo.  52249a. 
la.  Exterior  and  side  views  of  ventral  valve,  in  which  the  plications  are  stronger  than  in  the  specimen  repre- 
sented by  figure  1.     U.  S.  Nat.  Mus.  Cat.  No.  52249b. 
lb.  Dorsal  valve  flattened  in  the  shale.     U.  S.  Nat.  Mus.  Cat.  No.  52249c. 

Ic.  Exterior  and  side  views  of  rather  strongly  costate  dorsal  valve.     U.  S.  Nat.  Mus.  Cat.  No.  52249d. 
Id  and  Id'.  Top,  side,  and  back  views  of  a  cast  of  a  somewhat  quadrate  ventral  valve.     U.  S.  Nat.  Mus.  Cat. 

No.  52249e. 
le.  Top  and  side  views  of  the  ca.st  of  a  transverse  ventral  valve.     U.  S.  Nat.  Mus.  Cat.  No.  52249f.     Another 

specimen  (('at.  No.  52249g)  was  used  to  restore  certain  portions  of  this  figure. 
If.  Interior  of  a  dorsal  valve,  with  strongly  developed  median  ridge.     U.  S.  Nat.  Mus.  Cat.  No.  52249h. 
Ig.  Cast  of  the  interior  of  a  dorsal  valve,  having  very  strongly  marked  muscle  scars.     U.  S.  Nat.  Mus.  Cat.  No. 

522491. 
Ih.  Interior  of  a  dorsal  valve  with  strongly  marked  muscle  scars.     U.  S.  Nat.  Mus.  Cat.  No.  52249J.     The 

specimen  represented  occurs  on  the  same  hand  specimen  with  that  represented  by  figure  1  1. 
li.  Interior  of  a  dorsal  valve  that  should  be  compared  with  the  interior  represented  by  figure  If.     U.  S.  Nat. 

Mus.  Cat.  No.  52249k. 
Ij.  Cast  of  the  interior  of  a  dorsal  valve,  with  very  strong  muscle  scars.     U.  S.  Nat.  Mus.  Cat.  No.  52249  1. 
Ik.  Cast  of  the  interior  of  a  dorsal  valve,  with  strong  muscle  scars  and  vascular  sinuses.     U.  S.  Nat.  Mus.  Cat. 

No.  52249m. 
1  1.  Cast  of  the  interior  of  dorsal  valve,  with  rather  faintly  marked  muscle  scars.     U.  S.  Nat.  Mus.  Cat.  Xo. 

52249n.     This  specimen  is  associated  on  the  same  hand  specimen  with  the  specimen  represented  by 

figure  Ih. 

The  specimens  represented  are  all  from  Locality  320b,  Middle  Cambrian  limestones  of  ihe  Agnostus  Isevigatus  zone 
at  Gudhem,  12.5  miles  (20.1  km. )  south-southeast  of  Skara,  Province  of  Skaraborg,  Sweden. 

BiLLINGSELLA    EXPORRECTA    RUGOSICOSTATA  Walcott   (p.  755). 

Figure  2.  Top  and  side  views  of  a  cast  of  the  interior  of  a  \-entral  valve,  the  type  specimen,  having  very  strongly 
marked  costse.     U.  S.  Nat.  Mus.  Cat.  No.  52250a. 

2a.  Top  and  side  ^■iews  of  a  cast  of  the  interior  of  a  ventral  valve,  having  strongly  marked  costas  with  fine  radi- 
ating strise  upon  them.     f.  S.  Nat.  Mus.  Cat.  No.  522.50b. 

2b.  Top  and  side  views  of  a  cast  of  the  interior  of  a  dorsal  valve.     U.  S.  Nat.  Mus.  Cat.  No.  52250c. 

2c.  Top  and  side  views  of  a  cast  of  the  interior  of  a  dorsal  valve  less  strongly  costate  than  most  specimens  of 
this  variety.     U.  S.  Nat.  Mus.  Cat.  No.  52250d. 

The  specimens  represented  are  all  from  Locality  320b,  Middle  (^ambrian  limestones  of  the  Agnostus  Ixiigatus 
zone  at  Gudhem,  12.5  mUes  (20.1  km.)  south-southeast  of  Skara,  Province  of  Skaraborg,  Sweden. 
296 


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MONOGRAPH   Lt     PL.    lXxxv  II 


^SF^ 


if 'mm 


K 


/ 


PRANCES  WIESER  DEL. 


-lOTYPE    CO    eOSTOM 


PLATE    LXXXIX. 


297 


PLATE  LXXXIX. 

ct.  Cardinal  muscle  scar.  j.  Anterior  lateral  muscle  scar, 

d.  Dcllhyriuin.  vs.  Vascular  sinus, 

h.  Central  muscle  scar. 

BiLLINGSELLA    RICHTHOFENI    Walcott    (p.  761). 

Figure  1.  Exterior  of  ventral  valve,  the  type  specimen,  with  .^ide  outline,  from  Locality  C3,  Lower  Cambrian  Manto 
shale,  2.5  miles  (4  km.)  southwesit  of  Yenchuang,  Sintai  district,  Shantung,  China.  U.  S.  Nat. 
Mus.  Cat.  No.  52559a. 

WiMANELLA    SIMPLEX    Walcott    (p.  748). 
[Text  fig.  04,  p.  748.] 

Figure  2.  Ventral  valve  from  Locality  4v,  Lower  Cambrian  shale  on  Gordon  Creek,  6  miles  (9.6  km.)  from  the  South 

Fork  of  the  Flathead  River,  Ovando  quadrangle  (U.  S.  Cieol.  Survey),  Powell  County.  Montana. 

U.  S.  Nat.  Mus.  Cat.  No.  52278a.     Copied  from  Walcott  [190Sd.  PL  N.   fig.  2].     This  is  the  type 

specimen. 
2a,  2b,  and  2c.  Ventral  valves  of  varying  outlines  owing  to  distortion  in   the  shales  of  Locality  4w,  Lower 

Caml)rian  shales  on  Youngs  Creek,  about  5  miles  (8  km.)  from  its  junction  with  Danaher  Creek, 

Ovando  quadrangle  (U.  S.  Geol.  Survey),  Powell  County,  Montana.     U.  S.  Nat.  Mus.  Cat.  Nos. 

52277a-c,  respectively. 
2d.  Cast  of  interior  of  ventral  valve  associated  with  the  sjiecimens  represented  by  figures  2a-c.     V.  S.  Nat. 

Mus.  Cat.  No.  52277d. 
2e.  Ventral  and  dorsal  valves  compressed  and  resting  against  each  other  at  the  posterior  margins,  associated 

with  the  specimen  represented  by  figure  2.     V.  S.  Nat.  Mus.  Cat.  No.  5227Sb. 

Otusia  utahensis  "Walcott   (p.  770). 

Figure  3.  Transverse  dorsal  valve,  the  type  specimen,     l'.  S.  Nat.  Mus.  Cat.  No.  522Sla. 
3a.  Ventral  valve  with  rounded  cardinal  angles.     U.  S.  Nat.  Mus.  Cat.  No.  522Slb. 
3b.  Fragment  of  a  dorsal  valve.     U.  S.  Nat.  Mus.  Cat.  No.  52281c. 
3c.  Enlargement  of  outpr  surface.     U.  S.  Nat.  Mus.  Cat.  No.  52281d. 

The  specimens  represented  are  from  Locality  33r,  Middle  Cambrian  limestone  in  canyon  about  1  mile  (1.6  km.) 
east  of  Cricket  Spring.  Cricket  Range  (locally  known  as  the  Beaver  River  Range  or  the  Beaver  Mountains^  northwest 
of  Black  Rock.  Millard  County.  Utah. 

Wyxnia  warthi  (Waagen)   (p.  771). 

[Text  figs.  (;s.\  and  OSA',  p.  771.) 

Figure  4.  Cast  of  the  interior  of  the  ventral  valve  represented  Ijy  figure  4b.  showing  faint  muscle  area  and  strong 
vascular  sinuses.  This  figure  is  incorrect  and  is  superseded  by  text  figure  68A,  page  771,  which  see. 
Geol.  Survey  India  Cat.  No.  4  124.  The  area  of  this  specimen  was  figured  by  Waagen  [1891,  PI. 
II,  fig.  14].  " 

4a.  Cast  of  the  interior  of  another  ventral  ^•alve  showing  faint  muscle  area  and  strong  vascular  sinus.  Geol. 
Survey  India  Cat.  No.  4/122.     Type  specimen  figured  liy  Waagen  [1891,  PI.  I.  figs.  12a-b]. 

4b.  Area  of  the  specimen  represented  Ijy  figure  4.  The  small  deltidium  represented  in  the  drawing  is  a  mis- 
take; there  is  none  on  the  specimen.  The  delthjTium  is  much  too  large  in  the  drawing  owing  to  the 
breaking  away  of  the  point  of  the  beak.  The  specimen  is  correctly  represented  in  text  figure  68A', 
page  771,  which  see.  Geol.  Survey  India  Cat.  No.  4  124.  Specimen  figured  in  this  position  by 
W.iagcn  [1891,  PI.  II,  fig.  14]. 

4c.  Cast  of  the  interior  of  a  doi-sal  valve.  This  valve  is  fitted  in  its  proper  place  to  the  ventral  valve  repre- 
sented liy  figure  4a,  and  the  two  valves  probably  belong  to  tlie  same  specimen.  Geol.  .Survey  India 
Cat.  No.  4/122. 

4d,  4e,  and  4f.  Diagrammatic  figures  of  a  very  young  individual  showing  the  two  valves  united.  Copied 
from  Waagen  [1891.  PI.  II,  figs.  2a-c]. 

The  specimens  represented  are  all  from  Locality  357d,  Middle  Cambrian  concretionary  shales  of  the  Kliussak 
group  at  several  localities  between  Chel  Hill  and  Kiura  (Khewrai.  eastern  part  of  the  .Salt  Range.  India.     The  speci- 
mens represented  by  figures  4  and  4a  likely  occur  in  the  ^•icinity  of  Ch^l  Ilill.     Tliey  are  all  in  the  collection  of  the 
Geological  Survey  of  India. 
298 


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MONOGRAPH   LI     PL.   LXXXIX 


[...:.■■ 


3, 


\ 


^ 


FRANCES  WIESER  DEL. 


MELIOT/PE   ^C   SaSTON 


PLATE  LXXXIX.  299 

EooRTHis  KicHOUENsis   (Walcott)    (j).  782). 

Figures  5  and  5'.  Exterior  and  side  views  of  a  ventral  valve,  the  type  specimen,  from  Locality  C78,  Middle  Cambrian 
limestone,  Kichou  formation,  4.5  miles  (7.2  km.)  south  of  Wutaihien,  Shaiisi,  China.  U.  S.  Nat.  Mus. 
Cat.  No.  52550a. 

EooRTHis  AGRESTE   (Walcott)    (p.  773). 

Figure  6.  Exterior  and  side  views  of  a  ventral  valve,  the  type  specimen,  from  Locality  C28,   Middle  Cambrian 
Changhia  limestone  1  mile  (1.6  km.)  east-southeast  of  Changhia.  .Shantung,  China.     U.  S.  Nat.  Mus. 
Cat.  No.  52545a. 
Ga.  Enlargement  of  the  radiating  rilis  on  another  specimen.     U.  S.  Nat.  Mus.  Cat.  No.  52545b. 

EooRTHis  sp.  undt.  c  (Walcott)  (p.  793). 

Figure  7.  Exterior  and  side  views  of  a  small  ventral  valve  from  Locality  C26,  Middle  Canil)rian  Changhia  limestone 
2  miles  i3.2  km.)  north-northeast  of  Changhia,  Shantung,  China.     IT.  S.  Nat.  Mus.  Cat.  No.  52554a. 

EooRTHis  sp.  midt.  d  (Walcott)  (p.  793). 

Figure  8.  Exterior  of  a  ventral  valve  from  Locality  C71,  Middle  Cambrian  limestone,  Kichou  formation,  4  mileS 
(C.4  km.)  southwest  of  Tungyn,  Shansi,  China.     V.  S.  Nat.  Mus.  Cat.  No.  52555a 

HUENELLA    ETHERIBGEI   Walcott    (p.  S07). 

Figures  9  and  9'.  Top  and  side  views  of  a  dorsal  valve  from  Locality  315c.  Middle  ?  Cambrian.  Archseocyathinfe  white 
limestone  at  "Wirrialpa,  Flinders  Range,  South  Australia.  Type  specimen  in  the  collection  of  the 
LTniversity  of  Adelaide,  South  Australia;  cast  in  the  United  States  National  Museum,  Cat.  No.  53G78b. 
9a  and  9a'.  Top  and  side  views  of  a  ventral  valve  associated  with  the  specimen  represented  by  figure  9. 
Original  in  the  collection  of  the  University  of  Adelaide,  South  Australia;  cast  in  the  LTnited  States 
National  Museum,  Cat.  No.  53678a. 

The  figures  are  both  copied  from  Walcott  [1908d,  PL  X,  figs.  13a  and  13,  respectively].     They  represent  the 
specimens  illustrated  by  Etheridge  [1905,  PI.  XXV,  figs.  10  and  9,  respectively]  as  Orthis  (or  Orthlsina)  sp. 

DiCELLOMUS  PROLiFicus  Walcott   (p.  57S). 

FiGURE.s  10  and  10'.  Top  view  and  side  outline  of  a  broad  form  of  the  ventral  val\-e,  the  type  specimen.     IT.  S.  Nat. 
Mus.  Cat.  No.  51925a.     Copied  from  Walcott  [1908d,  PI.  VIII,  fig.  3]. 
10a  and  10a'.  Top  view  and  side  outline  of  a  narrow  ventral  valve.     U.  S.  Nat.  Mus.  Cat.  No.  51925c. 
10b  and  10b'.  Top  view  and  side  outline  of  dorsal  valve.     U.  S.  Nat.  Mus.  Cat.  No.  51925b.     Copied  from 
Walcott  [1908d.  PI.  VIII,  fig.  3a]. 

The  specimens  represented  are  all  from  Locality  lOz,  Middle  Cambrian  Marjum  limestone  in  the  long  cliff  about 
2  miles  (3.2  km.)  southeast  of  Marjum  Pass  [Walcott,  19081.  p.  179  and  Pis.  XIII  and  XV],  House  Range.  Utah. 

DiCELLOMUS  PARVUS  Walcott  (p.  574). 

Figure  11.  Top  ^^ew  of  partly  exfoliated  ventral  valve.     U.  S.  Nat.  Mus.  Cat.  No.  52523c. 

11a  and  lib.  Interiors  of  dcjr.sal  valves.     U.  S.  Nat.  Mus.  Cat.  Nos.  52o23a  and  52523b,  respectively.     Copied 
from  Walcott  [190Sd.  PI.  VIII,  figs.  2  and  2a,  respectively].     Figure  lib  represents  the  type  specimen, 
lie.  Exterior  of  a  dorsal  valve.     U.  S.  Nat.  Mus.  Cat.  No.  52523d. 
lid.  Exterior  of  a  young  shell.     I^.  S.  Nat.  Mus.  Cat.  No.  52.D23e. 

The  figures  represented  are  all  from  Locality  C6,  Middle  Cambrian  .shales,  Kiulung  group.  2.5  miles  (4  km. )  .south- 
west of  Yenchuang,  Sintai  district.  Shantung.  China. 


PLATE    XC. 


301 


PLATE  XC. 

a.  Cardinal  area.  d'.  Cast  of  umbonal  cavity, 
a'.  Anterior  adductor  impressions.  j.  Cardinal  process. 

b.  Dental  sockets.  o.  Ovarian  area:>. 

c.  Crura.  vs.  Vascular  sinus. 

BiLLINGSELLA    RETROFLEXA    (Matthew)     (p.  761). 

Figure  1 .  Cast  of  the  exterior  of  a  rather  coarsely  costate  ventral  valve.     University  of  Toronto,  Canada, 
la.  Cast  of  the  exterior  of  a  finely  costate  ventral  valve.     University  of  Toronto,  Canada. 
lb.  Cast  of  the  exterior  of  a  small,  compressed  ventral  valve,  with  a  strongly  marked  mesial  depression. 

University  of  Toronto,  Canada. 
Ic.  Matrix  of  the  exterior  of  a  large  dorsal  valve.     University  of  Toronto,  Canada.     Specimen  figured  by 

Matthew  [1903,  PI.  X,  fig.  2d]. 
Id.  Cast  of  the  e.xterior  and  side  outline  of  a  dorsal  valve.     University  of  Toronto,  Canada, 
le.  Enlargement  of  the  costse  and  radiating  striae,  as  shown  in  the  matrix  of  the  anterior  portion  of  the  shell 

University  of  Toronto,  Canada. 
If.  Cast  of  a  partly  exfoliated  dorsal  valve.     University  of  Toronto,  Canada. 
Ig.  Cast  of  the  interior  of  a  ventral  valve.     University  of  Toronto,  Canada.     Specimen  figured  by  Matthew 

[1895,  PI.  II,  fig.  lb]  as  Clilambonites  (Gonainbonitcs)  plana  retrojlaa.  • 

Ih.  Cast  of  a  portion  of  the  interior  of  a  ventral  valve,  in  which  portions  of  the  ca.st  of  the  outer  surface  of  the 

shell  are  preserved.     University  of  Toronto,  Canada.     Type  specimen  figured   by  Matthew  [1895, 

PI.  II,  fig.  la]  as  Clilamboniles  (Goiianibonites)  plana  retrojtexa. 

The  specimens  represented  are  all  from  Locality  307d,  Middle  Cambrian  sandy  limestone  on  Young  (McFees) 
Point,  near  George  Paver,  Cape  Breton,  Nova  Scotia. 

BiLLiNGSELL.v  KOMiNGERi  (BaiTande)   (p.  762). 

Figures  2,  2a-d.  Ventral,  dorsal,  side,  front,  and  posterior  views  of  the  type  specimen  in  which  the  two  valves  are 
united,  from  Locality  345f,  Middle  Cambrian  Etage  C,  near  Skrej,  Bohemia.  Figures  2,  2a-d  are  copied  from 
Barrande  [1879a,  Pl.'LXII,  figs.  II:  3a,  3c,  3b,  3d,  and  3e,  respectively]. 

Figure  2e.  Exterior  and  side  views  of  a  ventral  valve.     U.  S.  Nat.  Mus.  Cat.  No.  52267a. 

2f.  Matrix  of  ventral  valve  in  which  the  area  is  preserved.  U.  S.  Nat.  Mus.  Cat.  No.  52267b.  The  specimen 
is  on  the  same  hand  fragment  with  the  ventral  valve  .shown  in  figure  2h. 

2g,  2h,  and  2i.  Casts  of  the  interiors  and  side  outlines  of  ventral  valves.  L".  S.Nat.  Mus.  Cat.  Nos.  52267c, 
52267d,  and  52267e,  respectively.  The  specimen  represented  by  figure  2h  is  on  the  same  hand  frag- 
ment as  the  one  shown  in  figure  2f. 

2j.  Cast  of  interior  and  side  view  of  a  dorsal  valve.     U.  S.  Nat.  Mus.  Cat.  No.  52267f. 

2k.  Cast  of  the  interior  and  side  view  of  a  dorsal  valve  showing  very  strong  muscular  impressions.  V.  S.  Nat. 
Mus.  Cat.  No.  52267g. 

2  1.  Cast  of  the  interior  of  a  dorsal  valve.     U.  S.  Nat.  Mus.  Cat.  No.  52267h. 

2m.  Cast  of  the  interior  of  a  very  small  ventral  valve.     U.  S.  Nat.  Mus.  Cat.  Xo.  522G7i. 

2n,  2n',  and  2n".  Top,  posterior,  and  side  views  of  the  cast  of  the  interior  of  a  ventral  valve  in  which  the 
vascular  trunks  are  readily  traced  to  the  back  of  the  intcrinr  (if  the  b^>ak.  U.  S.  Nat.  Mus.  Cat.  No. 
522G7J. 

The  specimens  represented  by  figures  2e-n  are  from  Locality  345,  Middle  Cambrian  .^hale  on  the  I)h)uha  llnra, 
above  the  brook  of  Sbirov,  near  Skrej,  Bohemia. 
302 


U.  S.  GEOLOGICAL  SURVEY 


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FRANCES  WIESER  DEL. 


LiOTv^e   CO  BOSTON 


PLATE   XCI. 


303 


PLATE  XCI. 

b.  Dental  sockets.  d'.  Cost  ot  umbonal  cavity. 

c.  Crura.  i-  Cardinal  process. 

EooKTHis  REMNiCHA  (X.  H.  Wiiichcll)  (p.  786). 

[Text  ng.  7,  p.  299,  and  PI.  XCII,  figs.  2, 2a-d,  3,  3a-e.] 
FiouEES  1,  la.  and  11).  Casts,  taken  in  a  natural  mold,  of  ventral  valves  in  which  the  costa  and  mesial  sinus  show 

wide  variation  in  form.     U.  S.  Nat.  Mus.  Cat.  Nos.  52361a,  523011),  and  52361c  respectively. 
Ic.  Top  view,  with  side  and  back  outlines,  of  a  natural  cast  of  part  of  the  interior  of  a  ventral  valve.     The 

tripartite  divi.sion  of  the  interior  of  the  shell  (visceral  area)  opposite  the  deltidium  is  finely  shown. 

U.  S.  Nat.  Mus.  Cat.  No.  62361d. 
Id.  Natural  cast  ot  the  interior  of  a  ventral  valve,  with  strong  rounded  costse.     U.  S.  Nat.  Mus.  Cat.  No. 

52361e. 
le.  Natural  cast  of  the  interior  of  a  ventral  valve,  with  fine  costse  and  short  auricula te  extension  of  the  cardinal 

angles.     U.  S.  Nat.  Mus.  Cat.  No.  52361f. 
If  and  Ig.  Natural  casts  of  small  finely  costate  ventral  valves,  with  slightly  auriculate  cardinal  angles.      U.  S. 

Nat.  Mus.  Cat.  Nos.  52361g  and  52361h,  respectively. 
Ih.  Natural  cast  of  strongly  costate  ventral  valve,  with  short  cardinal  line.     Locality  80a,  Upper  Cambrian 

"  St.  Croix  sandstone  "  4  miles  (6.4  km.)  north  of  Reedsburg,  Sauk  County,  Wisconsin.     U.  S.  Nat.  Mus. 

Cat.  No.  523G2a. 
11.  Cast  in  natural  mold  of  a  ventral  valve,  with  short  cardinal  line,  strong  costse,  and  median  sinus.     U.  S. 

Nat.  Mus.  Cat.  No.  523611. 
Ij.  Natural  cast  of  a  small  ventral  valve,  with  very  strong  costse.     U.  S.  Nat.  Mus.  Cat.  No.  52361J. 
Ik.  Natural  cast  of  a  ventral  valve,  with  fine  costse  interspaced  between  strong  costse.     U.  S.  Nat.  Mus.  Cat. 

No.  52361k. 
1 1.  Natural  cast  of  a  ventral  valve,  with  strong  costa?  much  like  those  of  figure  Id.     A  gradation  of  the  strength 

of  the  costse  is  noticeable  from  figure  1 1  through  figiu-es  Id,  Ij,  lb,  Ic,  Ih,  If,  and  Ig.     The  specimen 

represented  liy  figure  11  is  associated  with  the  ventral  valve  shown  in  figure  Ih.     U.  S.  Nat.  Mus. 

Cat.  No.  52362b. 
Im,  In,  lo,  Ip,  and  Irj.  Natural  casts  of  dorsal  valves,  showing  variation  in  form  and  strength  of  surface  costse. 

U.  S.  Nat.  Mus.  Cat.  Nos.  52361 1-p,  respectively. 
Ir.  Enlargement  of  the  posterior  portion  of  figure  Iq.     U.  S.  Nat.  Mus.  Cat.  No.  52361p. 
Is.  Enlargement  of  the  surface  of  a  ventral  valve  from  Locality  12n,  Upper  Cambrian  limestone  of  the  Reagan 

sandstone,  sec.  1,  T.  2  S.,R.  1  E.,  Ardmore  quadrangle  (U.  S.  Geol.  Survey*.  Carter  County.  Okla- 
homa.    U.  S.  Nat.  Mus.  Cat.  No.  5235Ga. 

\Mth  the  exception  of  figures  Ih,  1 1,  and  Is  the  specimens  repre.sented  are  all  from  Localit\-  97a,  Upper  Cambrian 
"St.  Croix  sandstone  "  near  Winfield,  Jeffer.son  County.  Wisconsin. 

EOORTHIS    REMNICHA    WINFIELDENSIS   (Walcott)    (p.  788). 

Figure  2.  Exterior  and  side  views  of  a  cast  in  a  natural  mold  of  the  exterior  surface  of  a  ventral  valve,  the  type 
specimen.     U.  S.  Nat.  Mus.  Cat.  No.  52374a. 
2a,  2b,  and  2c.  Three  natural  casts  of  ventral  valves  that  illustrate  variation  in  form.     U.  S.  Nat.  Mus.  Cat. 

Nos.  52374b,  52374c,  and  52374d,  respectively. 
2d.  Exterior  and  side  views  of  natural  cast  of  exterior  of  dorsal  valve.     U.  S.  Nat.  Mus.  Cat.  No.  52.374e. 
2e.  Exterior,  side,  and  back  views  of  natural  cast  of  a  dorsal  valve.     U.  S.  Nat.  Mus.  Cat.  No.  52374f. 
The  specimens  represented  are  all   from  Locality  97a,  Upper  Caml>riaii  ''St.  Croix  sandstone"  near  Winfield, 
Jefferson  County,  Wisconsin. 

EooRTiiis  IDDINGSI  (Walcott)  (p.  780). 

Figure  3.  Ventral  valve.     The  outline  is   partly  restored  from  another  shell.      U.  S.  Nat.  Mus.  Cat.  No.  52340a. 

Type  specimen  figured  by  Walcott  [1899,  PI.  LXII,  fig.  la]  as  Eoorthis  rcmnicha. 
3a.  A  small  dorsal  valve.     U.  S.  Nat.  Mus.  Cat.  No.  52340b.     Specimen  figured  by  Walcott  [1S99,  PI.  LXII, 

fig.  lb]  as  Eoorthis  remnicha. 
3b.  Interior  of  a  ventral  valve.     U.  S.  Nat.  Mus.  Cat.  No.  52340c. 

The  specimens  represented  are  all  from  Locality  302c,  L^pper  Cambrian  shaly  limestone  on  south  side  of  Gallatin 
Valley,  Yellowstone  National  Park,  ^\'yonling. 

Eoorthis  papias  (Walcott)  (p.  78.5). 

Figure  4.  Top  and  side  views  of  the  type  and  oidy  specimen  of  the  species  in  the  collection.     Locality  61,  Middle 
Cambrian  shales  near  the  top  of  No.  6  of  the  Manuels  Brook  .section  [Walcott.  1891b.  p.  261].  east  side 
of  Manuels  Brook,  Conception  Bay.  Newfoundland.     U.  S.  Nat.  Mus.  Cat.  No.  52353a. 
304 


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FRANCES  WIESER  DEL. 


MELIOTYPG     CO    SOSTOtt 


PLATE    XCII. 


62667°— VOL  51,  pt  2—12 20  305 


PLATE  XCII. 

1).  Dental  sockets.  d'.  Umbonal  cavity, 

c.  Crura.  j.    Cardinal  process. 

EOORTHIS    REMNICHA    SULCATA    (Walcott)    (p.  787). 

Figures  1  and  lb.  Natural  cast  of  dorsal  valves  from  Locality  97a,  Upper  Cambrian  sandstone  near  Winfield,  Jefferson 
County,  Wisconsin.     U.  S.  Nat.  Mus.  Cat.  Nos.  52365a  and  52365b,  respectively, 
la  and  Ic.  Natural  casts  of  dorsal  valves  from  Locality  80a,  Middle  Cambrian  sandstone  4  miles  (6.4  km.) 
north  of  Reedsburg,  Sauk  County,  Wi-sconsin.     U.  S.  Nat.  Mus.  Cat.  Nos.  52366a  and  .52366b,  respec- 
tively.    Figure  la  represents  the  type  specimen. 

EooRTHis  REMNICHA  (N.  H.  Wincliell)  (p.  786). 

[Text  fig.  7,  p.  299,  and  PI.  XCI,  figs.  1,  la-s.) 

Figure  2.  E.xterior  of  dorsal  valve  from  Locality  302b,  Middle  Cambrian  limestones  near  Crowfoot  Ridgo,  Yellowstone 

National  Park,  Wyoming.     U.  S.  Nat.  Mus.  Cat.  No.  35215a.     Specimen  figured  by  Walcott  [1899, 

PI.  LXII,  fig.  1]. 
2a.  Interior  of  ventral  valve  from  Locality  302n,  Upper  Cambrian  limestone  on  south  side  of  Gallatin  Valley, 

Gallatin  County,  Montana.     U.  S.  Nat.  Mus.  Cat.  No.  52354a.     Specimen  figured  by  Walcott  [1899, 

PI.  LXI,  fig.  3a]. 
2b.  Interior  of  dor.sal  valve  associated  with  the  specimen  represented  by  figure  2a.     U.  S.  Nat.  Mus.  Cat. 

No.  52354b.     Specimen  figured  by  Walcott  [1899,  PI.  LXI,  fig.  3]. 
2c.  Enlargement  of  exterior  of  a  ventral  valve  associated  with  the  specimen  represented  by  figure  2,  showing 

fine  radiating  striae.     U.  S.  Nat.  Mus.  Cat.  No.  35215b.     Specimen  figured  by  Walcott  [1899,  PI. 

LXII,  fig.  Id]. 
2d.  Ventral  and  dorsal  valves  associated  with  the  specimen  represented  by  figure  2a,  showing  fine  radiating 

stria.     U.  S.  Nat.  Mus.  Cat.  No.  52354c.    Specimen  figured  by  Walcott  [1899,  PI.  LXII,  fig.  Ic]. 
3;  3a,  3a',  3a";  and.  3c.  Threeventral  valves  illustrating  variation  in  form  and  costae.    The  fine  radiating  striae 

so  characteristic  of  the  specimens  represented  by  figures  2c  and  2d  are  largely  exfoliated  with  the 

matrix.     A  few  traces  of  the  striae  are  shown  by  figure  3a.     Locality  12k,  Upper  Cambrian  limestone 

of  the  Reagan  sandstone,  sec.  35,  T.  1  S.,  R.  1  E.,  Ardmore  quadrangle.  Carter  County,  Oklahoma. 

U.  S.  Nat.  Mus.  Cat.  Nos.  52355a,  52355b,  and  52355c,  respectively. 
3b.  Ventral  valve  from  Locality  12n,  Upper  Cambrian  limestone  of  the  Reagan  sandstone,  sec.  1,  T.  2  S., 

R.  1  E.,  Ardmore  quadrangle.  Carter  County,  Oklahoma.     U.  S.  Nat.  Mus.  Cat.  No.  52356h. 
3d.  Broad  form  of  dorsal  valve  associated  with  the  specimen  represented  by  figure  3b.     L^.  S.  Nat.  Mus.  Cat. 

No.  52356c. 
3e.  Elongate  form  of  dorsal  valve  associated  with  the  specimen  represented  by  figure  3.     U.  S.  Nat.  Mus. 

Cat.  No.  52355d. 

EOORTHIS    REMNICHA    TEXANA   (Walcott)    (p.  787). 

Figures  4,  4';  4a;  and  4b.  Three  ventral  valves,  varying  in  form  and  surface  characters,  from  Locality  71,  Upper 
Cambrian  limestone  in  Cold  Creek  Canyon,  Burnet  County,  Texas.  U.  S.  Nat.  Mus.  Cat.  Nos.  52369a, 
52369b,  and  52369c,  respectively.     Figure  4  represents  the  type  specimen. 

4".  Back  \-iew  of  a  large  ventral  valve  associated  with  the  specimen  represented  by  figure  4c.  The  specimen 
can  not  be  located.     U.  S.  Nat.  Mus.  Cat.  No.  52370b. 

4c.  Dorsal  valve  from  Locality  12m,  Upper  Cambrian  Arbuckle  limestone,  sec.  2,  T.  2  S.,  R.  1  E.,  .Vrdmore 
quadrangle,  Carter  County,  Oklahoma.    U.  S.  Nat.  Mus.  Cat.  No.  52370a. 

4d,  4e,  4f,  and  4g.  Dorsal  valves,  varying  in  form  and  surface  characters,  ass.iciated  with  the  specimens 
represented  by  figures  4,  4a-b.     U.  S.  Nat.  Mus.  Cat.  No.^.  52369d-g,  respectively. 

306 


U.  S.   GEOLOGICAL  SURVEY 


MONOGRAPH  LI     PL.  XCII 


FRANCES  WIESER  OEL. 


HCt.lOTVP6   CO  BOSTON 


PLATE   XCIII. 


307 


PLATE  XCIII. 


a.  Cardinal  area. 

a'.  Anterior  udductor  impressions, 
a".  Posterior  adductor  impressions. 

b.  Dental  soeket.s. 
d.  Delthyrium. 

d'.  Cast  of  umbonal  cavity. 


j.  Cardinal  process. 

^■|\'ascular  markings. 

sp.  Free  spondylium  or  cast  of  it. 

t.  Teeth, 
vs.  Vascular  sinus. 


FlNKELNBURGIA    OSCEOLA    (Walcott)    ()).  7'.  15). 

Figures  1  and  lb.  Natural  cauls  of  ventral  valves  from  Locality  78,  Upper  Cambrian  .sandstone  in  quarry  near  St. 

Croix  River,  in  suburbs  of  Osceola,  Polk  County,  WLscon.sin.     U.  S.  Nat.  Mils.  Cat.  Nos.  52413a  and 

52413b,  respectively. 
la.  Natural  cast  of  ventral  valve  from  Locality  79b,  Upper  Cambrian  sandstone  near  Hudson,  St.  Croix 

County,  Wisconsin.     U.  S.  Nat.  Mus.  Cat.  No.  52415a. 
Ic  and  1(1,  Id',  and  Id".  Casts  of  the  interior  of  a  dorsal  and  a  ventral  valve  from  Locality  83',  Upper  Cam- 
brian sandstone  near  Trempealeau,  Trempealeau  County,  Wisoon,sin.     U.  S.  Nat.  Mus.  Cat.  Nos. 

52412a  and  52412b,  respectively.     Figure  Id  represents  the  type  specimen, 
le.  Natural  mold  of  exterior  of  dor.sal  vahe  associated  with  the  specimens  represented  by  figures  Ic  and  Id. 

U.  S.  Nat.  Mus.  Cat.  No.  52412c. 
If.  Cast  of  interior  of  dor.sal  valve  that  shows  casts  of  what  may  have  been  the  points  of  attachment  of  the 

adductor  muscles,  associated  with  the  specimens  represented  by  figures  Ic  and  Id.     U.  S.  Nat.  Mus. 

Cat.  No.  52412d. 
Ig.  Cast  of  the  interior  of  dorsal  valve  as.sociated  with  the  specimens  represented  by  figures  Ic  and  Id. .   U.  S. 

Nat.  Mus.  Cat.  No.  52412e. 
Ih.  Imperfect  cast  of  the  inferior  of  a  dorsal  valve  from  Locality  79a, Upper  Cambrian  sandstone  at  Menomo- 

nie,  Dunn  County,  Wisconsin.    U.  S.  Nat.  Mus.  Cat.  No.  52414a. 

FiNKELNBURGIA    FINKELNBLTJOI    (Walcott)    (j).  794). 

Figure  2.  Cast  of  interior  of  ventral  valve,  the  type  specimen.     What  may  be  the  cast  of  the  base  of  the  \asciilar 

trunks  is  .shown  (vs).  U.  S.  Nat.  Mus.  Cat.  No.  52410a. 
2a.  Cast  of  interior  of  ventral  valve,  with  outline  of  posterior  view,  showing  area  of  adductor  scars  (a'). 

U.  S.  Nat.  Mus.  Cat.  No.  52410b. 
2b.  Cast  of  the  interior  of  a  ventral  valve.     U.  S.  Nat.  Mus.  Cat.  No.  .52410c. 
2c.  Cast  of  the  inferior  of  a  dorsal  valve.     U.  S.  Nat.  Mus.  Cat.  No.  52410d. 
2d.  Cast  of  the  inferior  of  a  ventral  valve  with  the  bases  of  very  large  vascular  sinuses.     U.  S.  Nat.  Mus.  Cat. 

No.  52410e. 
2e.  Cast  of  interior  of  dorsal  valve,  with  back  and  .side  outlines.     U.  S.  Nat.  Mus.  Cat.  No.  52410f. 

The  specimen  represented  by  figure  2  is  from  Locality  83,  and  those  by  figures  2a-c  are  from  Locality  83'.  a  slightly 
lower  horizon,  both  in  the  Upper  Cambrian  sandstone  near  Trempealeau.  Tremjiealeau  County,  ^\'iscon^in. 

EooRTiiis?  DIABLO  (Walcott)    (p.  77s). 

Figure  3.  Cast  of  interior  of  ventral  valve,  the  type  specimen,  from  Locality  81b,  Upper  Cambrian  sandstone  near 
Devils  Lake,  Sauk  ('ounty,  Wisconsin.     U.  S.  Nat.  Mus.  Cat.  No.  52334a. 


Otusla  sandbergi  (N.  II.  Winchell)   (j).  769). 

Figures  4  and  4a.  Exterior  of  ventral  valves.     U.  S.  Nat.  Mus.  Cat.  Nos.  3.5214a  and  35214b,  respectively. 
4b.  Interior  of  dorsal  valve.     U.  S.  Nat.  Mus.  Cat.  No.  35214c. 
4c  and  4d.  Inferior  of  the  posterior  part  of  a  ventral  valve.     U.  S.  Nat.  Mus.  Cat.  No.  35214d. 

The  specimens  represented  are  all  from  Locality  302f,  Upper  Cambrian  limestone  on  north  side  of   Elk  Pass, 
Yellowstone  National  Park,  Wyoming. 
308 


U.  S.   GEOLOGICAL  SURVEY 


MONOGRAPH   U     PL.  XCIII 


=^RANCE8  WIESER  DEt 


MtLIOTVPE   CO   BOSTOM. 


PLATE  XCIII.  309 

Protorthis  wingi  Wal('ott  (p.  743). 

Figure  5.  Distorted  cast  of  interior  of  ventral  valve.     U.  S.  Nal.  Mns.  Cat.  No.  r)243Ta. 

5a.  Distorted  ventral  valve,  the  typo  specimen,  compreB.sed  in  argillaceous  shale.     U.  S.  Nat.  Mus.  Cat.  No. 

52437b. 
oh  and  oc.  Casts  of  distorted  dorsal  valves.     U.  S.  Nat.  Mus.  Cat.  Nos.  •^)24.37c  and  .52437d,  respectively. 

The  specimens  represented  are  all  from  Locality  28,  Ujjper  Cambrian  shales  about  100  feet  above  the  OUnellua 
horizon  south  of  Highgate  Falls,  0.25  mile  (0.4  km.)  east  of  •Swanton,  Franklin  County,  Vermont. 

NisusiA   (Jamesella)  nautes   (Walcott)    (p.  T.'A). 

Figures  0  and  Oa.  Exterior  of  ventral  valves  compressed  and  distorted  in  argillaceous  shale  of  Locality  163,  Middle 
Cambrian  Spence  shale  member  of  the  Ute  limestone  in  Spence  Gulch,  15  miles  (24.2  km.)  west  of 
Montpelier,  Bear  Lake  County,  Idaho.  U.  S.  Nat.  Mus.  Cat.  Nos.  152432a  and  52432b,  respectively. 
Figure  6  represents  the  type  specimen. 
6b.  Interior  of  dorsal  valve  associated  with  specimens  represented  by  figures  0  and  (ja.  U.  S.  Nat.  Mus.  Cat. 
No.  52432c. 

Nisusia  (Jamesella)  spencei  (Walcott)   (p.  7.37). 

[Text  fig.  62,  p.  737.] 

Figure  7.  Compressed  ventral  valve,  from  Locality  llq.  Middle  Cambrian  limestone  in  Ic  of  the  Marjum  limestone, 
in  ridge  east  of  \\lieeler  Amphitheater,  IIou.sc  Range,  ITtah.     U.  S.  Nat.  Mus.  Cat.  No.  52436a. 
7a.  Compressed  ventral  valve,  from  Locality  163,  .Middle  (.'ambrian  Spence  shale  member  of  the  Ute  limestone 
in  Spence  Gulch,  15  miles  (24.2  km. )  west  of  Montpelier,  Bear  Lake  County,  Idaho.     U.  S.  Nat.  Mus. 
Cat.  No.  52435b.     This  is  the  type  specimen. 


PLATE   XCIV. 


311 


PLATE  XCIV. 

EooRTHis  wiCHiTAENsis  (Walcott)  (p.  790). 

[I'l.  xciv.ng.  lu.] 

Figures  1  ami  1'.  Exterior  of  ventral  valve,  the  type  specimen,  and  view  of  area,  from  Locality  12p.  Upper  Cam- 
brian limestones,  at  the  northwest  extremity  of  the  Arl)uckle  Mountains.  al)out  4  miles  (0,4  km.  I  east 
of  Homer,  Carter  County,  Oklahoma.     U.  S.  Nat.  Mus.  Cat.  No.  52384a. 

laand  la'.  Exterior  of  ventral  valve  showingslight  mesial  fold,  with  side  view.  Locality  12k,  Upper  Cambrian 
limestones  in  sec.  35,  T.  1  S.,  R.  1  E.,  Ardmore  quadrangle,  Carter  County,  Oklahoma.  U.  S.  Xat. 
Mus.  Cat.  No.  52383a. 

lb  and  lb'.  Exterior  of  ventral  valve  associated  with  the  specimen  represented  by  figure  1,  showing 
flattened  mesial  area.     U.  S.  Nat.  Mus.  Cat.  No.  52384b. 

Ic  and  Ic'.  Exterior  of  ventral  valve  associated  with  the  specimen  represented  by  figure  la.  U.  S.  Nat.  Mug. 
Cat.  No.  52383b. 

Id.  Exterior  of  ventral  valve  from  Locality  71,  Middle  Cambrian  limestone  in  Cold  Creek  Canyon,  Burnet 
County,  Texas.     U.  S.  Nat.  Mus.  Cat.  No.  52379a. 

le.  Ventral  valve  partly  exfoliated  posteriorly  so  as  to  show  cast  of  muscle  area,  associated  with  the 
specimen  represented  by  figure  1.     U.  S.  Nat.  Mus.  Cat.  No.  52384c. 

If.  Exterior  of  ventral  valve,  with  straight  cardinal  slopes,  associated  with  the  specimen  represented  by 
figure  1.     U.  S.  Nat.  Mus.  Cat.  No.  52384d. 

Ig  and  Ih,  Ih'.  Exterior  views  of  two  dorsal  valves  illustrating  variation  in  form  and  surface  characters, 
associated  with  the  specimen  represented  by  figure  1.  U.  S.  Nat.  Mus.  Cat.  Nos.  52384e  and  52384f, 
respectively. 

li.  Exterior  of  dorsal  valve  associated  with  the  specimen  represented  by  figure  Id.  U.  S.  Nat.  Mus.  Cat. 
No.  52379li. 

Ij.  Ij',  and  Ik.  Exteriors  of  two  dorsal  valves  associated  with  the  specimen  represented  by  figure  la.  U.  S. 
Nat.  Mus.  Cat.  Nos.  52383c  and  52383d,  respectively. 

11  and  Im.  Dorsal  valves  associated  with  the  specimen  represented  by  figure  1.  U.  S.  Nat.  Mus.  Cat.  Nos. 
52384g  and  52384h.  respectively. 

In.  Dorsal  valve  from  Locality  12n,  ITpper  Cambrian  limestones  in  sec.  1,  T.  2  S.,  R.  1  E..  Ardmore  quad- 
rangle. Carter  County,  Oklahoma.     U.  S.  Nat.  Mus.  Cat.  No.  52381a. 

lo.  Cast  of  interior  of  a  dorsal  valve  from  Locality  68,  Upper  Cambrian  limestone  in  Packsaddle  Mountain, 
Llano  County,  Texas.     U.  S.  Nat.  Mus.  Cat.  No.  52382a. 

EOORTHIS    WICHITAENSIS    LiEVIUSCULUS   (Walcott)    (p.  791). 

Figures  Ip,  Iq.  Ir,  and  Is.  Ventral,  dorsal,  side,  and  posterior  views  of  the  type  specimen,  a  complete  shell  free  from 
matrix,  from  Locality  12p,  ITpper  Cambrian  limestones,  at  the  northwest  extremity  of  the  Arbuckle 
Mountains,  about  4  miles  (6.4  km.)  east  of  Homer,  Carter  County,  Oklahoma.  U.  S.  Nat.  Mus.  Cat. 
No.  52396a. 

EOORTHIS    INDIANOLA   (Walcott)    (p.   780). 
[PI.  XCW.figs.  2,  2a-h.l 

Figure  It.  Dorsal  valve  from  Locality  12k,  I'pper  Cambrian  limestones,  Ardmore  quadrangle.  Carter  County.  Okla- 
homa.    U.  S.  Nat.  Mus.  Cat.  No.  52343a. 

Figure  lu.  Fragment  of  limestone  from  Locality  14b,  Upper  Cambrian  limestone  on  Cold  Creek,  Llano  County,  Texas, 
illustrating  association  of  forms  of  Eoorthis  wichiluensis  (W)  and  Eoorthis  indiannla  (X).  I^.  S.  Nat. 
Mus.  Cat.  No.  52380a. 

Eoorthis  wichitaensis  (Walcott)  (p.  790;. 

[PI.  XCn'.flgs.  l,la-o.I 

Figure  1\i.  Fragment  of  limestone  from  Locality  14b,  Upper  Cambrian  limestone  on  Cold  Creek,  Llano  County,  Texas, 
illustrating  association  of  forms  of  Eoorthia  wichitaensis  (W)  and  Eoorthis  indianola  (X).     U.  S.   Nat. 


strating 
Mus.  Cat.  No.  52380a 


312 


U.  S.   GEOLOGICAL  SURVEY 


MONOGRAPH   LI     PL.  XCIV 


PC    CS    BOSTON 


PLATE  XCIV.  313 

EOORTHIS    INDIANOLA   (Walcott)    (p.   7S0). 
[PI.  XCIV,  figs.  It-u.) 

Figure  2.  Exterior  of  a  ventral  valve,  the  type  specimen,  enlarged  to  show  surface  costje  and  strise.     U.  S.  Nat. 

Mus.  Cat.  No.  52343b. 
2a.  Exfoliated  ventral  valve  showing  cast  of  vi.sceral  area.     Locality  12p,  Upper  Cambrian  limestones  at  the 

northwest  extremity  of  the  Arlmckle  Mountains,  about  4  miles  ( (1.4  km. )  east  of  Homer,  Carter  County, 

Oklahoma.     U.  S.  Nat.  Mus.  Cat.  No.  52342a. 
2b,  2b';  2c,  2d,  and  2e.  Exterior  of  four  ventral  valves  that  vary  in  form  and  surface  characters.     U.  S.  Nat. 

Mus.  Cat.  No.  52343c-f,  respectively. 
2f  and  2f'.  Exterior  and  side  outline  of  dorsal  valve.     U.  S.  Nat.  Mus.  Cat.  No.  52343g. 
2g  and  2g'.  Ventral  valve  associated  with  the  specimen  represented  by  figure  2a.     U.  .S.  Nat.  Mus.  Cat.  No. 

52342b. 
2h.  Exterior  of  dorsal  valve.     U.  S.  Nat.  Mus.  Cat.  No.  o2343h. 

■\\'ith  the  exception  of  figures  2a  and  2g  the  specimens  represented  are  all  from  Locality  12k,  Upper  Cambrian 
limestones  in  sec.  35,  T.  1  S.,  R.  1  E.,  Ardmore  quadrangle.  Carter  County,  Oklahoma. 

EOORTHIS    HASTINGSENSIS   (Walcott)    (p.  779). 

Figures  3  and  3'.  Exterior  view  and  side  outline  of  ventral  valve  from  Locality  21,  Middle  Cambrian  limestone  at 
the  base  of  the  Paradoxides  zone  on  Hanford  Brook,  St.  John  County,  New  Brunswick.  U.  S.  Nat. 
Mus.  Cat.  No.  52337a.     This  is  the  type  specimen. 

3a.  Diagrammatic  outline  of  a  vertical  median  section  through  the  united  valves  of  a  specimen  associated 
with  the  ventral  valve  represented  by  figure  3.     U.  S.  Nat.  Mus.  Cat.  No.  52337b. 

3b  and  3c,  3c'.  View  of  exterior  of  ventral  and  dorsal  valves,  with  side  outline  of  dorsal  valve,  from  Locality 
2s,  Middle  Cambrian  limestone,  at  Hastings  Cove,  on  Kennebeca.sis  Bay,  northeast  of  St.  John,  New 
Brunswick.     U.  S.  Nat.  Mus.  Cat.  Nos.  52336a  and  5233Gb,  respectively. 


PLATE   XCV. 


315 


PLATE  XCV." 

a'.  Anterior  adductor  scars.  c.  Crura, 

a".  Posterior  adductor  scars.  j.  Cardinal  process, 

b.  Dental  sockets.  r.  Diductor  .soars. 

EooRTiiis  CHRisTiANLE  (Kjerulf) "  (p.  775). 

Figure  1.  Cast  of  e.Ktcrior  of  ventral  valve.     U.  S.  Nat.  Mu.-<.  Cat.  No.  52.306h. 

la, -lb,  and  Ic.  Casts  of  ventral  valves  showing  muscular  area.     U.  S.  Nat.  Mus.  Cat.  Nos.  52306a-c,  respec- 
tively. 
Id,  le,  and  If.  Casts  of  exterior  of  dorsal  valves.     U.  S.  Nat.  Mus.  Cat.  Nos.  52.306d-f,  re.spectively. 
Ig.  Cast  of  interior  of  dorsal  valve.     U.  S.  Nat.  Mus.  Cat.  No.  o230Gg. 

The  specimens  represented  by  figures  1,  la-gare  from  Locality  310d,  Upper  Cambrian  Ceralopyge  slate  at  Borghr)lm, 
Oeland  Lsland,  Sweden. 

Figure  Ih.  Dorsal  valve  with  strong  median  sinus,  from  Locality  323x,  Upper  Cambrian  Ceralopyge  slate  at  Rus- 
s?l6kken,  near  Christiania,  Norway.     U.  S.  Nat.  Mus.  Cat.  No.  52307a. 

EooRTHis  DAUNUS  (Walcott) ''  (p.  776). 

Figure  2.  Ventral  valve  with  side  outline  from  Locality  310j,  passage  beds  between  the  Upper  Cambrian  and  the 

Ordovician,  Ceratopyge  limestone  at  Borgholm,  Oeland  Island,  Sweden.     V.  S.  Nat.  JIus.  Cat.  No. 

52309a. 
2a  and  2b.  Dorsal  valves  in  limestone  matrix  of  Locality  323z,  passage  beds  between  the  Upper  Cambrian  and 

the  Ordovician,   Ceratopyge  limestone  at  Toien,  near  Christiania,  Norway.     L'.  S.  Nat.  Mus.  Cat. 

Nos.  52308a  and  52308b,  respectively.     Figure  2a  represents  the  type  specimen. 
2c.  Dorsal  valve  associated  with  the  .specimen  represented  by  figure  2.     I'.  S.  Nat.  Mus.  Cat.  No.  52309b. 

EOORTHIS    TULLBERGI    (Walcott)"   (p.  790). 

FidURE  3.  Partly  exfoliated  ventral  valve,  the  type  specimen,  from  Locality  390,  passage  beds  between  the  Upper  Cam- 
brian and  the  Ordovician,  at  Alunbruk  (alum  works\  Oeland  Island,  Sweden.  U.  S.  Nat.  Mus.  Cat. 
No.  58309. 

EooRTHis  wiMAXi  (Walcott) "  (p.  791). 

Figure  4.  Cast  of  interior  of  ventral  valve  from  Locality  8x,  passage  beds  between  the  Upper  Cambrian  and  the  Ordo- 
vician, Ceratopyge  limestone  at  Slemmostad,  about  3  miles  (4.8  km.)  southwest  of  Christiania,  Norway. 
U.  S.  Nat.  Mus.  Cat.  No.  52311a. 

4a.  Cast  of  interior  of  dorsal  valve,  the  type  specimen,  from  Locality  323w,  L'pper  Cambrian  lilack  argil- 
laceous shale  of  "Etage  3a/}"  at  Christiania,  Norway.     L'.  S.  Nat.  Mus.  Cat.  No.  52;il3a. 

4b.  Exfoliated  dorsal  valve  from  Locality  310j,  passage  bids  between  the  L'pper  Cambrian  and  the  Ordovician, 
Ceratopyge  limestone  at  Borgholm,  Oeland  Island,  Sweden.     V.  S.  Nat.  Mus.  Cat.  No.  52312a. 

4c  and  4d.  Ventral  and  dorsal  valves  associated  with  the  specimen  represented  by  figure  4a.  V.  S.  Nat.  Mus. 
Cat.  Nos.  52313b  and  52313c,  respectively. 

Protorthis?  hunnebergensis  Walcott"  (p.  740). 

Figure  5.  Cast  in  shale  of  exterior  of  ventral  valve.    U.  S.  Nat.  Mus.  Cat.  No.  .52428a. 

5a.  Cast  of  compressed  ventral  valve,  the  type  specimen.     U.  S.  Nat.  Mus.  Cat.  No.  52428b. 
5b.  Cast  in  shale  of  exterior  of  dorsal  valve.     U.  S.  Nat.  Mus.  Cat.  No.  52428c. 
5c.  Partial  cast  of  interior  of  dorsal  valve.     U.  S.  Nat.  Mus.  Cat.  No.  5242Sil. 

The  specimens  represented  are  all  from  Locality  ,390f,  pa.ssage  beds  between  the  Upper  Cambrian  and  the  Ordo- 
vician, shales  at  Mossebo,  on  Hunneberg,  Province  of  Skaraborg,  Sweden. 


o  A  photograph  of  this  plate  was  sent  to  Prof.  J.  C.  Moberg,  who  reproduced  It  as  Plate  II  ol  his  paper  on  the  Ceralopyge  region  (Moberg  and 

Segerberg,  1900,  I'l.  11]. 

81 G 


U.  S.  GEOLOGICAL  SURVEY 


MONOGRAPH    LI     PL.  XCV 


PHANCES  WIESeR  DEL. 


MCLiatVPE   CO  aOSTOM 


PLATE  XCV.  817 

EOSTROPIIOMENA    ELEGANTULA    (Willcott)"    (p.  796). 

Figure  6.  Exterior  of  ventral  valve,  the  type  specimen.     U.  S.  Nat.  Mu.s.  Cat.  No.  5231Ga. 
6a.  Tartly  exfoliated  dorsal  valve.     U.  S.  Nat.  Mus.  Cat.  No.  52316b. 

6b.  Cast  of  Interior  of  dor.sal  valve.     All  elevations  and  depressions  are  the  reverse  of  their  actual  occurrence 
in  the  interior  of  the  shell.     U.  S.  Nat.  Mus.  Cat.  No.  52316c. 

The  specimens  represented  are  all  from  Locality  310j,  passage  beds  between  the  Upper  Cambrian  and  the  Ordo- 
vician,  Ccrafopyge  limestone  at  Borgholm,  Oeland  Island,  Sweden. 

EooKTHis  ATAVA  (Matthew)"  (p.  774). 

Figures  7  and  7a.  Ventral  valves.     Figure  7  represents  the  type  specimen. 
7b.  Dorsal  valve. 

The  specimens  represented  are  all  from  Localily  308a,  Upper  Cambrian  shales  of  Division  C3a  of  Matthew  at  Navy 
Island,  St.  John  Harbor,  St.  John,  New  Brunswick.  The  figures  (7,  7a-b)  are  redrawn  from  the  specimens  illustrated 
by  Matthew  [1893,  PI.  VII,  figs.  8c,  8a,  and  8b,  respectively]. 

a  A  photograph  of  this  plate  was  sent  to  I'rot.  J.  C.  Moberg,  who  reproduced  it  as  Plate  U  of  his  paper  on  the  Ceralopyge  region  [Moberg  and 
Segerberg,  1906,  PI.  IIJ. 


PLATE   XCVI. 


319 


PLATE  XCVI. 

c.  Crura.  ps.  Pseudospondylium. 

j.  Cardinal  process.  s.  Median  septum, 

t.  Teeth. 

EooRTHis  DESMOPLEURA  (Meek)  (p.  777). 

FiGBRES  1;  la,  la';  lb;  and  If.  Exterior  and  side  view.s  of  four  ventral  valvep,  illustratinj;  variation  in  form  and 
surface  characters.  Locality  187,  Lower  Ordovician  red  siliceous  limestone  105-122  feet  above  the 
pre-Cambrian,  2  miles  (3.2  km.)  below  JIanitou  Park  Hotel,  El  Paso  County,  Colorado.  L'.  S.  Nat. 
Mus.  Cat.  Xos.  52317a-d,  re.spectively. 

Id  and  le.  Cast  of  ventral  valve  associated  with  the  specimen  represented  by  figure  1,  with  side  outline,  show- 
ing area  and  cast  of  umbonal  cavity.    U.  S.  Nat.  Mus.  Cat.  No.  52317e. 

If  and  Ig.  Dorsal  valves  associated  with  the  specimen  represented  by  figure  1.  V.  S.  Nat.  JIus.  Cat.  Nos. 
52317f  and  52317g,  respectively. 

Ih.  Silicified  shell  showing  character  of  radiating  costse  and  stria;.  This  is  the  type  specimen,  from  Locality 
360f,  Lower  Ordo\'ician  siliceous  limestone  at  Glen  EjTe,  Camp  Creek  Canyon,  near  Manitou,  El 
Paso  County,  Colorado.     V.  S.  Nat.  Mus.  Cat.  No.  7859a. 

li  and  Ij.  Top  and  side  views  of  ventral  valves  from  Locality  14k,  I^pper  Cambrian  limestone  on  Wolf  Creek. 
15  miles  (24.2  km.)  west -southwest  of  Sheridan,  Sheridan  County,  Wyoming.  U.  S.  Nat.  Mus.  Cat. 
Nos.  52320a  and  52320b,  respectively. 

Ik  and  1 1.  Exterior  of  dorsal  calves  associated  with  the  dorsal  valves  represented  by  figures  li  and  Ij.  U.  S. 
Nat.  Mus.  Cat.  Nos.  52320c  and  52320d,  respectively. 

Im  and  In.  Exterior  of  small  ventral  valves.     U.  S.  Nat.  Mus.  Cat.  Nos.  52319a  and  52319b,  respectively. 

lo.  Exterior  of  a  ventral  valve.    V.  S.  Nat.  Mus.  Cat.  No.  52319c. 

Ip.  Side  view  of  a  young,  convex  shell.     V .  S.  Nat.  Mus.  Cat.  No.  52319d. 

Iq.  Posterior  portion  of  the  interior  of  an  abraded  ventral  valve.     L'.  S.  Nat.  Mus.  Cat.  No.  52319e. 

Ir.  Interior  of  an  abraded  dorsal  valve.    U.  S.  Nat.  Mus.  Cat.  No.  52319f. 

The  specimens  represented  by  figures  Im-r  are  from  Locality  168,  Middle  Cambrian  limestones  on  Tepee  Creek, 
near  the  road  from  Sheridan  to  Dome  Lake,  Bighorn  Mountains,  Wyoming. 

EOORTHIS    DESMOPLEURA    NYMPHA    (Walcott)    (p.  778). 

Figure  2.  Exterior  and  side  views  of  a  \-entral  \ahe,  the  type  specimen,  from  Locality  168,  Middle  Cambrian  lime- 
stones on  Tepee  Creek,  near  the  road  from  Sheridan  to  Dome  Lake,  Bighorn  Jlountains,  ^^■yoming. 
U.  S.  Nat.  Mus.  Cat.  No.  52333a. 

Plectorthis  whitfieldi  (X.  H.  Winchell)  (p.  308). 

Figure  3.  Interior  of  a  ventral  valve,  showing  the  relatively  high  area  and  strong  teeth,  the  outline  of  the  pseudo- 
spondylium, and  the  low  ridges  extending  forward  and  outward  from  its  anterior  margin.  Ordovician, 
Spring  Valley,  Minnesota.     Copied  from  Hall  and  Clarke  [lS92c,  PI.  V,  fig.  26]. 

Plectorthis  plicatella  (Hall)  (p.  772). 

[Text  fig.  12,  p.  299.] 

Figure  4.  Posterior  portion  of  the  interinr  of  a  \i'ntral  valve,  showing  the  broad  delthyrium.  teeth,  and  the  outline 
of  the  pseudospondylium. 
4a.  The  area  of  the  dorsal  valve,  showing  the  triangular  delthyrium,  cardinal  process,  crural  plates,  and  low 
narrow  median  ridge. 

The  specimens  represented  are  all  from  the  Ordovician  at  Covington,  Keritu<ky.     The  figures  are  copied  from  Hall 
and  Clarke  [1892c,  PI.  V,  figs.  19  and  20]. 
320 


U.  S.   GEOLOGICAL  SURVEY 


MONOGRAPH  LI     PL.  XCVI 


^ 


ilA-i*^- 1     'iJiL 


'^ikH^h^..^  \ 


<^m 


,^  f/^ 


"^iiX'l 


i^ii 


5" 


^ 


u 


i     > 


0')  m 


FRANCES  WiESER  DEL. 


ELIOTVPC    CO    eOSTOM 


PLATE  XCVI.  321 

Plectorthis  jamesi  (Hall)  (p.  772). 

Figure  5.     Exterior  of  a  ventral  valve.     U.  S.  Nat.  Mus.  Cat.  No.  51307a. 
5a.  Interior  of  a  ventral  valve.     U.  S.  Nat.  Mus.  Cat.  No.  513C7b. 
5b.  Interior  of  a  dorsal  valve.     U.  S.  Nat.  Mus.  Cat.  No.  51307c. 

5c.  View  of  the  interior  of  the  specimen  represented  by  figure  5b  over  the  front  margin  so  as  to  obtain  a  front 
view  of  the  cardinal  process  and  crural  plates. 

The  specimens  represented  are  all  from  Ordovician  beds  of  Lorraine  age  at  Cincinnati,  Ohio,  and  the  figures  are 
introduced  here  for  comparison. 

Plectorthis  parva  (Dalman)  (p.  776)." 

Figure  6.  Exterior  of  a  ventral  valve,  to  illustrate  form  and  surface  ribs.     U.  S.  Nat.  Mus.  Cat.  No.  52314a. 

6a-d.  Side  views  of  four  specimens  having  the  two  valves  united,  to  illustrate  the  variation  in  the  convexity 

of  young  and  adult  shells.     U.  S.  Nat.  Mus.  Cat.  Nos.  52314b-e,  respectively. 
6e.  Interior  of  a  ventral  valve.     U.  S.  Nat.  Mus.  Cat.  No.  52314f. 
6f.  Interior  of  a  dorsal  valve..    U.  S.  Nat.  Mus.  Cat.  No.  52314g. 
6g.  Enlargement  of  the  posterior  portion  of  the  interior  of  a  dorsal  valve,  to  show  the  small  cardinal  process, 

etc.     U.  S.  Nat.  Mus.  Cat.  No.  52314h. 

The  locality  and  horizon  of  the  specimens  represented  are  unknown. 

a  See  Eoorthis  christianix,  p.  776. 
62667°— VOL  51,  pt  2—12 21 


PLATE    XCVII. 


323 


PLATE  XCVII. 

EooRTHis  PRiMORDiAi.is   (tie  \'cnicuil  and  Biiriando)  (p.  785). 

FicJURE   I.  Ventral  view  of  the  type  specimen,  having  the  two  valves  nnited. 
la.  Dorsal  view  of  the  specimen  represented  by  figure  1. 

lb.  The  same,  seen  from  the  side.     The  area  of  the  dorsal  valve  is  a  little  loo  .short. 
Ic.  The  same,  posterior  view. 
Id.  The  same,  seen  from  the  front  side.     Most  of  our  specimens  are  less  thick. 

The  specimen  represented  is  from  Locality  350,  Middle  Cambrian  limestone  near  Adrados,  Cantabrian  Mountains, 
Province  of  Leon,  Spain.     The  figures  are 'copied  from  de  Verneuil  and  Harrande  [1860,  PI.  VIII,  figs.  G,  Ca-<1]. 

NisusiA   (Jamesella)   pellico   (dc  Verneuil  and  Barrande)  (p.  735). 

Figure  2.  Ventral  view  of  the  type  specimen,  showing  area  and  deltidiuin. 
2a.  Dorsal  view  of  the  specimen  represented  by  figvire  2. 
2b.  Posterior  view  of  same,  showing  areas  of  valves. 

The  specimen  represented  is  from  Locality  350,  Middle  Cambrian  limestone  near  Adrados,  Cantabrian  Mountains, 
Province  of  Leon,  Spain.     The  figures  are  copied  from  de  Verneuil  and  Harrande  [18(i0.  PI.  VII,  figs.  7,  7a-b]. 

NiSUSiA  ?  VATICINA    (de  Yeiiieiiil  and  Barrande)  (]).  7.30). 

Figure  3.  Dorsal  view  of  the  type  specimen,  with  the  two  valves  united,  showing  the  area  of  the  ventral  valve. 
3a  and  31).  Posterior  and  side  views  of  same  shell. 

The  specimen  represented  is  from  Locality  350,  Middle  Cambrian  limestone  near  Adrados,  Cantabrian  Mountains, 
Province  of  Leon,  Spain.     The  figures  are  cojjied  from  de  Verneuil  and  Barrande  [1800,  PI.  A'lII,  figs.  S,  Sb-c]. 

EooRTHis  BAVARICA   (Barrande)  (p.  775). 

Figure  4.  A  distorted  ventral  valve,  the  type  specimen,  from  Locality  303c,  passage  beds  between  the  Upper  Cam- 
brian and  Ordovician,  suburbs  of  Hof,  Bavaria.     Copied  from  Barrande  [1868a,  fig.  76]. 

EooRTHis  LiNNARSSONi  (Kayser)  (p.  782). 

Figure  5.  Dorsal  valve  from  Locality  C64,  Upper  Cambrian  limestone  2.7  miles  (4.4  km.)  southwest  of  Yenchuang, 
Sintai  district,  Shantung,  China.     U.  S.  Nat.  Mus.  Cat.  No.  52.549a. 
5a.  Ventral  and   dorsal  valves   from   Locality   332a,  LTpper   Cambrian   at    Taling.  Liaotung,  China.     Type 
specimen  copied  from  Kayser  [1883,  PI.  Ill,  fig.  1]. 

EooRTHis  KAYSERi   (Walcott)    (j).  782). 

Figure  6.  Partly  exfoliated,  distorted  ventral  valve.     U.  S.  Nat.  Mus.  Cat.  No.  52546a. 

6a.  Partly  exfoliated  dor.sal  valve,  the  tyi)e  specimen.     U.  S.  Nat.  Mus.  Cat.  No.  52546b. 
Gb.  Cast  of  tlic  interior  of  a  dorsal  valve.     U.  S.  Nat.  Mus.  Cat.  No.  52546c. 

The  specimens  represented  are  all  from  Locality  064,  I'jjper  Cambrian  limeslone  2.7  miles  (4.4  km.)  southwest  of 
Yenchuang,  Sintai  district,  Shantung,  China. 

BiLLiNGSELLA  iiicKsi  (Saltef  MS.)  (Davidsoii)  (p.  756). 

Figures  7  and  7a.  Ventral  and  dorsal  views  of  the  type  specimen. 
7b.  Cast  of  ventral  valve. 

The  specimens  represented  are  from  Localities  318d  and  318p,  Middle  Caml)rian  sandstones  in  the  Menevian  at 
Porth-y-rhaw  and  Ninewells,  near  Si.  Davids,  South  Wales;  Davidson  does  not  say  which.     Figures  7,  7a-b  are  copied 
from  Davidson  [1869,  PI.  XXXIII,  figs.  14a,  13a,  and  IGa,  resi)ectively]. 
324 


U.  S.   GEOLOGICAL  SURVEY 


MONOGRAPH   LI     PL.  XCVII 


FRANCES  WIESER  DEL. 


MELIOTVPE  CO.,    BOSTON 


PLATE  XCVII.  325 

B1LLINGSELI.A  puMPELLYi  Walcott  (p.  760). 

Figure  8.  Top  and  side  view  of  partly  exfoliated  ventral  valve,  the  type  specimen,  from  Locality  C61,  Upper  Cam- 
brian limestone  3  miles  (4.8  km.)  southwest  of  Yenchuang,  Sintai  district.  Shantung,  China.  U.  S. 
Nat.  Mus.  (.'at.  No.  .52.558a. 

8a.  Top  and  side  view  of  cast  of  a  ventral  valve  from  Locality  C36,  Upper  Cambrian  Chaumitien  limestone 
at  Chaumitien,  Changhia  district,  Shantung,  China.     U.  S.  Nat.  Mus.  Cat.  No.  52557a. 

8b.  Interior  of  dorsal  valve  associated  with  the  specimen  represented  by  figure  8a.  U.  S.  Nat.  Mus.  Cat. 
No.  52557b. 

8c.  Enlargement  of  outer  surface,  near  front  margin,  of  a  shell  associated  with  the  specimen  represented  by 
figure  8.     V.  S.  Nat.  Mus.  Cat.  No.  52.558b. 

EooRTHis  NEWTONENsis  (Weller)  (p.  784). 

Figures  9  and  9a.  Cast  of  interior  of  ventral  and  dorsal  valves,  with  side  outline  of  ventral  valve  (9'),  from  Locality 
lie,  Upper  Cambrian  Uardyston  quartzite,  O'Donnell  and  McManniman's  quarry,  Newton,  Sussex 
County,  New  Jersey.     U.  S.  Nat.  Mus.  Cat.  Nos.  52352a  and  52352b,  respectively. 

EooRTHis  jOHANNENsis  (Matthew)  (p.  781). 

Figure  10.  Top  and  side  views  of  ventral  valve,  the  type  specimen.     University  of  Toronto,  Canada. 
10a.  Top  and  side  views  of  dorsal  valve.     University  of  Toronto,  Canada. 

The  specimens  represented  are  both  from  Locality  308b,  Upper  Cambrian  limestone  in  shales  of  Division  C3a  of 
Matthew,  Germaine  Street,  St.  John,  St.  John  County,  New  Brunswick.  The  figures  are  redrawn  from  the  specimens 
illustrated  by  Matthew  [1892,  PL  XII,  figs.  13a-c]  as  Orthisina  (?)  johannensh. 

EooRTHis  SALTENsis  (Kayser)   (p.  788). 

Figure  11.  Group  of  .-ihells  on  fragment  of  rock  from  Locality  389,  Upper  Cambrian  sandstone  at  Salta,   Argentina. 
Type  specimen,  copied  from  Kayser  [1876,  PL  I,  fig.  16]. 
11'.  Casts  of  two  ventral  valves  on  fragment  of  rock  from  Locality  389a,  Upper  Cambrian  sandstone  at  Nevado 
de  Castillo,  Province  of  Salta,  Argentina.     Copied  from  Kayser  [1876,  PI.  I,  fig.  15]. 

EooRTHis  PAGODA   (Walcott)    (p.  784). 

Figures  12  and  12a.  Partly  exfoliated  ventral  \-alves.     U.  S.  Nat.  Mus.  Cat.  Nos.  52552a  and  52552b,  respectively. 
Figure  12  represents  the  type  specimen. 
12b.  Partly  exfoliated  dorsal  valve.     U.  S.  Nat.  Mus.  Cat.  No.  52552c. 
12c.  Interior  of  dorsal  valve.     U.  S.  Nat.  Mus.  Cat.  No.  52552d. 
12d.  Enlargement  of  a  portion  of  the  outer  surface  of  the  shell.     U.  S.  Nat.  Mus.  Cat.  No.  52552e. 

The  specimens  represented  are  all  from  Locality  C56.  Upper  Cambrian  (  hauniitien  limestone  at  Pagoda  Hill, 
1  mile  (1.6  km.)  west  of  Tsinan,  Shantung,  China. 

EooRTHis  DORIS  (Walcott)  (p.  779). 

Figure.s  13  and  13a.  Top  and  side  views  of  two  ventral  valves  from  Locality  C64,  Upper  Cambrian  limestone  2.7  miles 
(4.4  km.)  southwest  of  Yenchuang,  Sintai  district.  Shantung,  China.  U.  S.  Nat.  Mus.  Cat.  Nos.  52.551a 
and  52551b,  respectively.     Figure  13a  represents  the  type  specimen. 

NisusiA  COMPTA   (Tate)   (p.  727). 

Figure  14.  Top  and  side  views  of  the  type  specimen  of  the  .species  from  Locality  315,  Middle?  Cambrian  limestone 
at  Curramulka,  Yorke  Peninsula,  South  Australia.  University  of  Adelaide,  South  Australia.  Speci- 
men figured  by  Tate  1 18112,  PI.  II,  figs.  6  and  6a]  as  Orlhisina  compta. 

EooRTHis  TATEi  (Etlieridge)   (p.  789). 

Figure.?  15,  1.5',  and  1.5a,  1.5a'.  Top  and  side  views  of  ventral  and  dorsal  valves  from  Locality  315b,  Middle?  Cambrian 
limestone  at  Wirrialpa,  Flinders  Range,  South  Australia.  University  of  Adelaide,  South  Australia. 
Figures  15  and  15a  are  redrawn  from  the  specimens  illustrated  by  Etheridge  [1905,  PL  XXV,  figs. 
7  and  8,  respectively].     Figure  15a  represents  the  type  specimen. 


PLATE   XCVIII. 


327 


PLATE  XCVIII. 

Orusia  lenticularis  (Walilenberg)   (p.  765). 

[I'l.  XCVIII,  Hgs.fi.Oa-o.) 

Figures  1;  la,  la';  and  lb.  Exterior  surface  of  ventral  valves,  illustrating  variation  in  radial  costse,  with  side  outline 
of  specimen  represented  by  figure  la.  Locality  3S0n,  Upper  Cambrian  limestone  at  Hunneberg, 
Province  of  Skaraborg,  Sweden.     U.  S.  Nat.  Mus.  Cat.  Nos.  52400a-c,  respectively. 

Icand  Ic'.  Top  and  posterior  \aews  of  \'entral  \'alve  associated  vrilh  the  specimens  represented  by  figures 
1,  la-h.  Figures  Ic  and  2b  represent  forms  having  the  characters  of  Matthew's  "Orusia  lenticularis 
strophomenoides."     V.  S.  Nat.  Mus.  Cat.  No.  52400d. 

Id  and  Id'.  Top  and  side  views  of  a  smooth  ventral  valve  associated  with  the  specimens  represented  by 
figures  1,  la-b.     U.  S.  Nat.  Mus.  Cat.  No.  52400e. 

le  and  le'.  Natural  mold  of  the  interior  of  ventral  valve,  with  posterior  outline.  Locality  310a,  Upper  (  am- 
brian  shales  of  Olenus  truncatus  zone  on  Oeland  Island,  Sweden.     U.  S.  Nat.  Mus.  Cat.  No.  52406a. 

If,  If,  and  If".  Top,  side,  and  posterior  views  of  a  very  smooth  ventral  valve  associated  with  the  specimen 
represented  by  figure  le.     U.  S.  Nat.  Mus.  Cat.  No.  5240Gb. 

Ig  and  Ig'.  Top  and  side  views  of  a  dorsal  \alve  associated  with  the  specimen  represented  by  figure  le.  U.S. 
Nat.  Mus.  Cat.  No.  52406c. 

Ih,  li,  Ij,  Ik,  1  1,  Im,  In,  and  lo.  Series  of  dorsal  valves  and  side  outlines  illustrating  variation  in  form  of 
shell  and  character  of  surface.  Locality  390n,  Upper  Cambrian  limestone  at  Hunneberg,  Province 
of  Skaraborg,  Sweden.     U.  S.  Nat.  Mus.  Cat.  Nos.  52400f-m,  respectively. 

Ip.  Cast  of  the  interior  of  a  small  ventral  valve,  showing  the  extension  of  the  main  vascular  sinuses  back 
across  the  umbonal  cavity;  also  the  division  of  the  muscle  area  between  them  by  a  narrow  septum. 
This  specimen  is  in  the  tray  with  the  specimens  represented  by  figures  le-g,  but  none  of  the  speci- 
mens received  locality  numbers  when  they  were  first  collected  and  the  locality  may  be  con.sidered 
doubtful.     U.  S.  Nat.  Mus.  Cat.  No.  52406d. 

2  and  2'.  Top  and  side  views  of  a  ventral  valve  from  Locality  3,  Upper  Cambrian  limestone  300  feet  above 
the  Paradoxides  zone  on  Manuels  Brook,  Conception  Bay,  Newfoundland.  U.  S.  Nat.  Mus.  Cat. 
No.  52402a. 

2a.  Ventral  valve,  with  numerous  radiating  costse,  from  Locality  6v,  L^ppcr  Cambrian  limestones  325  feet 
above  the  Middle  Cambrian  on  Manuels  Brook,  Conception  Bay,  Newfoundland.  U.  S.  Nat.  Mus. 
Cat.  No.  52404a. 

2b.  A  small,  very  convex,  and  rugose  ventral  valve  in  which  the  radiating  costse  are  nearly  obliterated, 
associated  with  the  specimen  represented  by  figure  2a.  Figures  Ic  and  2b  represent  forms  having 
the  characters  of  Matthew's  "  Orusia  hnlicularis  strophomenoides."    U.  S.  Nat.  Mus.  Cat.  No.  52404b. 

2c  and  2d.  Compressed  ventral  valves  associated  with  the  sj)ecimen  represented  by  figure  2.  U.  S.  Nat. 
Mus.  Cat.  Nos.  52402b  and  52402c,  respectively. 

2c'.  Side  outline  of  specimen  represented  by  figure  2o. 

2e,  2f,  2h,  2i,  and  2j.  Series  of  dorsal  valves  associated  with  the  specimen  represented  by  figure  2,  illus- 
trating variation  in  form  of  shell  and  surface  characters.  U.  S.  Nat.  Mus.  Cat.  Nos.  52402d-h, 
respectively. 

2f'.  Posterior  view  of  specimen  represented  by  figure  2f. 

2g.  Dorsal  valve  associated  vrith  the  specimen  represented  by  figure  2a.     U.  S.  Nat.  Mus.  Cat.  No.  52404c. 

2k.  Compressed  ventral  valve  associated  with  the  specimen  represented  by  figure  2.  V.  S.  Nat.  Mus.  Cat. 
No.  524021. 

3.  Enlargement  of  a  fragment  of  shale  on  which  the  shells  show  a  considerable  variation. 

3a  and  3b.  Ventral  and  dorsal  valves. 

The  specimens  represented  by  figures  3,  3a-b  are  in  the  collection  of  the  Univer.«ity  of  Toronto,  Canada,  and  sire 
labeled  as  coming  from  St.  John,  New  Brunswick.  They  are  among  the  material  used  by  Matthew  in  drawing  figures 
9a-<l  of  his  paper  [1892,  PI.  XII],  but  closer  identification  is  impossible. 

Orusia  lenticulaki.s  ly.ncioides  (MatUiew)  (p.  769). 

Figure    4.  Ventral  valve  from  Lcxality  308b.  I'pik  r  Cambrian  lim(sli>ne  in  shales  of  Dix-ision  C3a  of  Matthew,  Gor- 
maine  Street,  St.  John,  New  Brunswick.     University  of  Toronto,  Canada.     Type  specimen  figured 
by  Matthew  [1892,  PI.  XII,  fig.  lOaJ. 
328 


U.  S.   GEOLOGICAL  SURVEY 


MONOGRAPH   l;      PL     XCVIM 


PRANCES  WIESER  DEL. 


PC   c::   sosroN 


PLATE  XCVIII.  329 

Orusia  lenticularis  atrypoides  (Matthew)  (p.  769). 

Figure  5.  Ventral  valve  from  Locality  308b,  Upper  Cambrian  limestone  in  shales  of  Division  C3a  of  Matthew,  Ger- 
maine  Street,  St.  John,  New  Brunswick.  University  of  Toronto,  Canada.  Type  specimen  figured 
by  Matthew  [1892,  PI.  XII,  fig.  11a]. 

Orusia  lenticxjlaris  (Wahlenberg)  (p.  TG.'S). 

[PI.  XCVIII,  figs.  :,la-p;  2,2a-k;  and  .3,3a-l>.) 

Figures  6,  6a-c.  Ventral,  dorsal,  side,  and  po.sterior  views  of  a  specimen  from  Locality  3,  Upper  Cambrian  limestones 
300  feet  above  the  Paradoxides  zone  on  Manuels  Brook,  Coneeption  Bay,  Newfoundland.  U.  S. 
Nat.  Mus.  Cat.  No.  52402J. 


PLATE    XCIX. 


331 


PLATE  XCIX. 

a.  Cardinal  area.  f.  Cast  of  dental  sockets. 

b.  Dental  sockets.  pc.  rseudocTuraliiim. 

d.  Delthyrium.  sp.  Free  spondylium  or  cast  of  it. 

d'.  Cast  of  didnctor  scars.  t.  Teeth. 

Protorthis  billingsi  (Hartt)   (p.  739). 

Figure  1.  Cast  of  ventral  valve  from  a  natural  mold,  in  which  the  area  i.s  compressed  and  crowded  backward.     V.  S. 

Nat.  Mus.  Cat.  No.  52424a. 
la.  Natural  cast  of  compressed  ventral  valve.     U.  S.  Nat.  Mus.  Cat.  No.  52424b. 
lb,  lb',  and  Id,  Id'.  Top  and  back  views  of  natural  casts  of  compressed  ventral  valves  in  which  the  area  is 

shown.     Id'  shows  the  cast  of  the  spondylium.     T.  S.  Nat.  Mus.  Cat.  Nos.  52424c  and  52424d, 

respectively. 
Ic.  Natural  cast  of  a  compressed  ventral  valve  (locality  unknown).    University  of  Toronto,  Canada, 
le  and  If.  Natural   casts   of  compressed   dorsal   valves.     U.   S.   Nat.  Mus.   Cat.   Nos.   52424e  and  52424f, 

respectively. 
Ig.  Natural  cast  of  the  outer  surface  of  a  small  dorsal  valve.     U.  S.  Nat.  Mus.  Cat.  No.  52424g. 

With  the  exception  of  figure  Ic  the  specimens  represented  are  all  from  Locality  3b,  Middle  Cambrian  shale,  head 
of  Seeley  Street,  St.  John,  St.  John  County,  New  Brunswick.     None  of  them  has  been  figured  before. 

Protorthis  quacoensis  (Matthew)  (p.  742). 

Figure  2.  Exterior  of  a  compressed  ventral  valve. 

2a.  A  minute  ventral  valve  referred  to  this  species. 

2b.  Top,  side,  and  posterior  views  of  the  cast  of  an  uncompressed  ventral  valve,  showing  elevation,  cardinal 

area,  and  deltidium.    Type  specimen,  figured  by  Matthew  [1886,  PI.  V,  figs.  20b  and  20c]. 
2c.  An  uncompressed  dorsal  valve,  with  posterior  and  side  view  in  outline. 
2d.  Dorsal  \a\ve  distorted  by  compression  and  movement  in  the  shale. 
2e.  Top  and  posterior  views  of  the  cast  of  a  dorsal  valve.     Specimen  figured  by  Matthew  [18S6,  PI.  V,  figs. 

20  and  20a]. 

The  specimens  represented  are  from  Division  Ic  of  Matthew's  Etcheminian,  but  Matthew  does  not  state  [1886, 
pp.  44  or  82]  whether  they  are  from  Porters  Brook  (Locality  301mi  or  Portland  (Locality  SOlgi.  St.  John  County, 
New  Brunswick.     They  are  all  in  the  collections  of  the  University  of  Toronto,  Canada. 

Protorthis  latourensls  (Matthew)  (p.  741). 

Figures  3  and  3'.  Mold  of  interior  of  a  dorsal?  valve,  with  side  outline  (locality  unknown").     University  of  Toronto, 

Canada. 
3a.  Matrix  in  fine  shale  of  the  exterior  of  a  ventral  valve  from  Locality  308h,  Middle  Cambrian  shales  of 

Division  Icl  at  Portland,  St.  John,  New  Brunswick.     U.  S.  Nat.  Mus.  Cat.  No.  1818.5a. 
3b.  Posterior  view  of  mold  of  a  ventral  valve  showing  mold  of  spondylium  (locality  unknown).     Uni\ersity 

of  Toronto,  Canada. 
3c.  Posterior  view  of  the  mold  of  a  ventral  valve  (locality  unknown).    University  of  Toronto,  Canada. 
3d.  Matrix  of  exterior  of  a  dorsal  valve  from  Locality  301w,  Middle  Cambrian  shales  of  Division  ]c2  of  Matthew 

ut  Portland,  St.  John,  New  Brunswick.     U.  S.  Nat.  Mus.  Cat.  No.  18168a. 

Figures  3,  3b,  and  3c  were  drawn  from  specimens  in  Matthew's  original  material,  but  none  of  the  Bpecimens 
represented  by  Matthew  in  figures  IS,  18a-c  [18S(i,  PI.  V]  is  redrawn  in  this  monograph. 

Protorthis  Helena  Walcott  (p.  740). 

Figure  4.  Cast  of  ventral  valve,  the  type  specimen,  from  Locality  2u,  Middle  Cambrian  shale  on  south  side  of  Long 
Island,  Kennebccasis  Bay,  St.  John  County,  New  Brimswick.     U.  S.  Nat.  Mus.  Cat.  No. -524273. 
4a  and  4b.  Side  and  back  views  of  the  specimen  represented  by  figure  4. 
332 


U.   S.   GEOLOGICAL  SURVEY 


MONOGRAPH   LI     PL.  XCIX 


FRANCES  WIE8ER  DEL. 


MEllOTyCC    CO    SOSTOm 


PLATE  XC'IX.  333 

Pkotorthis  (Loperia)  dugaldensis  Walcott  (]).744). 

Figures  5,  5',  and  5".  Top,  side,  and  posterior  views  of  a  niolil  of  ihe  interior  of  a  ventral  valve,  the  type  specimen. 

IT.  S.  Nat.  Mua.  Cat.  No.  52440a. 
5a.  A  compressed  and  distorted  ventral  valve  from  Locality  2u,  Middle  Cambrian,  south  side  of  Long  Island, 

Kennebecasis  Bay,  St.  John  County,  New  Brunswick.     LT.  S.  Nat.  Mus.  Cat.  No.  52446a. 
5b.  Side  outline  of  the  natural  mold  of  a  ventral  valve.     U.  S.  Nat.  Mus.  Cat.  No.  52440b. 
5b'.  View  looking  from  front  margin  toward  the  area  and  spondylium,  as  shown  in  a  cast  of  a  ventral  valve. 

Same  specimen  as  represented  by  figure  5b. 
5c  and  5c'.  Top  and  side  views  of  the  natural  mold  of  a  ventral  valve.     The  outline  5c'  shows  the  position  of 

the  short  spondylium  just  beneath  the  beak.     U.  S.  Nat.  Mus.  Cat.  No.  52440c. 
5d;  5e,  5e';  5f,  5f';  5g;  and  5h,  5h'.  Top  and  side  views  of  natural  molds  of  five  dorsal  valves,     V.  S.  Nat. 

Mus.  Cat.  Nos.  52440d-h,  respectively. 
51.  Enlargement  of  the  outer  surface  obtained  by  making  a  cast  from  the  matrix  of  the  surface.    U.  S.  Nat. 

Mus.  Cat.  No.  524401. 
5j.  Exterior  of  a  ventral  valve,  drawn  from  impressions  obtained  in  a  natural  matrix.     U.  S.  Nat.  Mus.  Cat. 

No.  52440]. 

The  specimens  represented  by  figs.  5,  5b-j  (not  5a)  are  from  Locality  lOp.  Middle  Camlirian  sandstones  of  Division 
E2b  of  Matthew  on  Dugald  Brook,  Indian  River,  Cape  Breton,  Nova  Scotia. 

Protorthis  Levis' Walcott  (p.  741). 

Figures  6,  6a,  and  6b.  Top,  back,  and  side  views  of  the  type  specimen,  from  Locality  79a,  Upper  Cambrian  "St. 
Croix  sandstone"  0.5  mile  (0.8  km.)  southeast  of  the  county  courthouse,  Menomonle,  Dunn 
County,  Wisconsin.     I'.  S.  Nat.  Mus.  Cat.  No.  52429a. 


PLATE    C. 


335 


PLATE  C. 

a.  Cardinal  area.  d'.  Cast  of  pscudocniralium. 

1).  Dental  sockets.  e.  Adduclor  soars. 

c.  Crura.  >■•  Diductor  scars, 
cr.  Pseudoeruraliuni.  t.  Teeth. 

d.  Deltidium.  ^-  Flexure  line. 

NiSUSIA    FESTINATA    (Billuigs)     (p.  727). 
[Text  flg.  (i,  p.  299.] 

Figure  1.  Exterior  of  ventral  valve,  drawn  from  mold  taken  in  a  natural  cast.     U.  S.  Nat.  Mus.  Cat.  Xo.  52288a. 

la.  Cast  of  ventral  valve  from  Locality  26a,  Lower  Cambrian  limestone  2  miles  (3.2  km.)  ea-st  of  Swanton, 

Franklin   County,  Vermont.     U.  S.  Nat.    Mus.    Cat.    Xo.    153.38a.     Specimen   figured   by  Walcott 

[188(ib.  PI.  VII,  fig.  7]. 
lb,  lb',  and  lb".  Top,  side,  and  back  views  of  cast  of  transvcr.-^e  ventral  valve.     U.  S.  Nat.  Mus.  Cat.  Xo. 

62288b. 
Ic  and  Ic'.  Top  and  side  views  of  cast  of  elevated  ventral  valve,  willi  strongly  marked  cost«.      U.  S.  Nat. 

Mus.  Cat.  No.  52288c. 
Id  and  Id'.  Top  and  back  views  of  cast  of  ventral  valve,  an  intermedialo  form  lietween  those  represented 

l)y  figures  lb  and  Ic.     U.  S.  Nat.  Mus.  Cat.  No.  52288d. 
Id".  Side  view  of  ventral  valve,  with  finer  cost;*  than  that  represented  liy  ligure  Id.     U.  8.  Nat.  Mus.  Cat. 

No.  52288e. 
le,  le'.  and  le".  Top,  side,  and  back  views  of  a  cast  taken  in  a  tialural  mold  of  a  ventral  valve,  in  which 

the  area  slopes  forward.     U.  S.  Nat.  Mus.  Cat.  No.  52288f. 
If  and  IF.  Top  and  side  views  of  a  cast  of  a  dorsal  valve.     U.  S.  Nat.  Mus.  Cat.  No.  52288g. 
Ig.  Cast  of  the  interior  of  a  large  dorsal  valve.     The  reference  of  the  markings  at  "e"  as  adductor  scars  is 

doubtful.     U.  S.  Nat.  Mus.  Cat.  No.  52288h. 
Ih  and  Ih'.  Top  and  liack  views  of  a  small  ventral  valve,  from  Locality  26,  Lower  Cambrian  sandstone  east 

of  Highgate  Springs,  Franklin  County,   Vermont.     U.   S.  Nat.  Mus.  Cat.   No.  15362a.     Specimen 

figured  liy  Walcott  [1886b.  PI.  VII,  figs.  7a-l)]. 
li  and  li'.  Top  and  side  views  of  cast  of  a  small  transverse  dorsal  valve.     L'.  S.  Xat.  Mus.  Cat.  No.  52288i. 
Ij.  Interior  of  a  ^•entral  \-alve  drawn  from  a  cast  of  a  natural  mold.     L".  S.  Nat.  Mtis.  Cat.  No.  52288J. 

With  the  exception  of  specimens  shown  liy  figures  la  and  Ih,  all  of  the  specimens  represented  by  figiu-es  1.  la-j 
are  from  Locality  49,  Lower  Cambrian  decomposed  arenaceous  limestones  on  Codorus  Creek,  below  Meyer's  mill,  near 
Emigsville,  Pennsylvania. 

Figures  2,  2';  2a,  2a';  and  2b,  2b'.  Top  and  side  views  of  three  ventral  valves  from  Locality  2o,  Lower  Cambrian 
conglomeratic  limestones  at  Bic,  Province  of  Quebec,  Canada.     U.  S.  Xat.  Mus.  Cat.  Nos.  52291a, 
52291b,  and  52291c,  respectively. 
2c,  2c'.  and  2c".  Top,  posterior,  and  side  views  of  a  ventral  valve,  with  point  of  the  apex  broken  off.     Asso- 
ciated with  the  specimens  represented  by  figures  2,  2a-b.     U.  S.  Nat.  Mus.  Cat.  No.  .52291d. 

NiSUSIA    ALBERTA    (Walcott)     (p.  726). 

Figure  3.  Top  and  side  ^dewof  a  cast  of  a  ventral  valve.  It  is  attached  to  the  dorsal  valve  shown  in  figure  3a. 
U.  S.  Nat.  Mus.  Cat.  No.  24070a.     The  type  specimen  is  represented  by  figures  3,  3a-b. 

3a.  View  of  a  cast  of  a  dorsal  valve,  and  the  area  of  the  ventral  valve  shown  in  figure  3.  V.  S.  Xat.  Mus.  Cat- 
No.  24070a. 

3b.  Posterior  view  of  the  ventral  and  dorsal  valves  represented  by  llgm-es  3  and  3a.  U.  S.  Nat.  Mus.  Cat. 
No.  24070a. 

3c.  Cast  of  exterior  surface  showing  ribs  and  stout  bases  of  spines.  V .  S.  Nat.  Mus.  ( 'at.  Xo.  240701).  Copied 
from  Walcott  [1908c,  PI.  I,  fig.  4]. 

3d.  Interior  of  the  largest  shell  seen.     Geol.  Survey  Canada.     Cojued  from  Walcott  [1908c,  PI.  I,  fig.  4a]. 

The  specimens  represenled  are  all  from  Locality  14s,  Middle  Cambrian  ()<j\j(jopsis  zone  on  Mount  Stephen,  aliove 
Field,  British  Columbia. 

NiSUSIA    FESTINATA    TRANSVERSA  (AValcott)    (j).  729). 

Figures  4  and  4a.  The  two  specimens  on  which  the  species  was  founded.    I'.  S.  Nat.  Mus.  Cat.  Nos.  15361a  and 
15361b,  respectively.     Specimens  figured  by  Walcott  [18S6l>.  PI.  VII.  figs.  5  and  5a]  as  Orlhisina 
traitsrrrsn.     Figure  4  represents  the  type  specimen. 
4b.  Interior  of  a  ventral  valve.     V.  S.  Nat.  Mus.  Cat.  No.  52293a. 

The  specimens  represenled  are  all  from  Locality  25.  Lower  Cambrian  sandstone  just  above  Parker's  quarry, 
near  Georgia,  Franklin  County,  Vermont. 
336 


U.  S.   GEOLOGICAL  SURVEY 


MONOGRAPH    U     PL.  C 


PRANCES  WIESER  DEL. 


HCLIOTVPE   CO   BOSTOM 


PLATE   CI. 


62667°— VOL  51,  pt  2—12 22  337 


PLATE  CI. 

a.  Cardinal  area.  d'.  Cast  of  iimbonal  cavity. 

b.  Dental  sockets.  dl.  Delthyrium. 

c.  Crura.  e.  Adductor  scars. 

d.  Deltidiuin.  j.  Cardinal  process. 

NisusiA   (Jamesella)  perpasta  (Pompeckj)  (p.  735). 

Figures  1  and  la.  Exterior  and  side  views  of  a  strongly  costate  ventral  valve  from  Locality  34Sk,  Lower  Cambrian 

sandstones  at  Slapnicky  Ml^n,  near  Skrej,  Bohemia.     U.  S.  Nat.  Mus.  Cat.  No.  52302a. 
lb  and  Ic.  Casts  of  exterior  of  ventral  valves  associated  with  the  specimen  represented  by  figures  1  and  la. 

U.  S.  Nat.  Mus.  Cat.  Nos.  52302b  and  52302c,  respectively. 
Id,  Id',  and  Id".  Summit,  back,  and  side  \'iews  of  cast  of  exterior  of  ventral  valve  from  Locality  345i,  Lower 

Cambrian  conglomeratic  sandstones  of  the  Kamenni  hurka,  near  Tejfovik,  Bohemia.    U.  S.  Nat. 

Mus.  Cat.  No.  52301a. 
le.  Cast  of  a  dorsal  valve  associated  with  the  specimen  represented  by  figures  1  and  la.     U.  S.  Nat.  Mus.  Cat. 

No.  52302d. 
If.  Cast  of  a  dorsal  valve  associated  with  the  specimen  represented  by  figure  Id.     V.  S.  Nat.  Mus.  Cat.  No. 

52301b. 
Ig.  Front  view  of  cast  of  ventral  valve  from  Locality  3451,  see  figure  Id.     Copied  from  Pompeckj  [1896b,  PI. 

XV,  fig.  16d]. 
Ih.  Cast  of  dorsal  valve  associated  with  the  specimen  represented  by  figures  1  and  la.     U.  S.  Nat.  Mus.  Cat. 

No.  52302e. 

NisusiA  (Jamesella)  perpasta  subquadrata  (Pompeckj)  (p.  7.36). 

Figure  2.  Cast  of  ventral  valve  from  Locality  3451,  Lower  Cambrian  conglomeratic  sandstones  of  the  Kamenni  hflrka, 

near  Tejrovik,  Bohemia.    U.  S.  Nat.  Mus.  Cat.  No.  52304a. 
2a.  Cast  of  ventral  valve  from  the  locality  represented  by  figure  2.     Type  specimen,  copied  from  Pompeckj 

[189Gb,   PI.  XV,  fig.  19a]. 
2b.  Cast  fit  dorsal  valve  from  the  locality  represented  by  figure  2.     Copied  from  Pompeckj  [1896b,  PI.  XV, 

fig.  20a]. 

NisusiA  (Jamesella)  perpasta  macra  (Pompeckj)  (p.  736). 

Figure  3.  Cast  of  ventral  valve  doubtfully  referred  to  this  variety  from  Locality  3451,  Lower  Cambrian  conglomeratic 
sandstones  of  the  Kamennd  hurka,  near  Tejrovik,  Bohemia.    U.  S.  Nat.  Mus.  Cat.  No.  52303a. 
3a.  Cast  of  dorsal  valve  from  the  locality  represented  by  figure  3.     Type  specimen,  copied  from  Pompeckj 
[lS96b,  PI.  XV,  fig.  14]. 

NisusiA  (Jamesella)  kuthani  (Pompeckj)  (p.  732). 

Figures  4  and  4'.  Cast  of  exterior  of  ventral  valve,  with  back  view.    U.  S.  Nat.  Mus.  Cat.  No.  2G643a. 

4a,  4a',  and  4a".  Summit,  back,  and  side  views  of  a  cast  of  a  ventral  valve.     U.  S.  Nat.  Mus.  Cat.  No. 

26643b. 
4b.  Cast  of  dorsal  valve.     U.  S.  Nat.  Mus.  Cat.  No.  26643c. 

The  specimens  represented  are  all  from  Locality  345i,  Lower  Cambrian  conglomeratic  sandstones  of  the  Kamennd 
hflrka,  near  Tejfovik,  Bohemia. 

NisusLv  (Jamesella)  erecta  Walcott  (p.  732). 

Figures  5,  -58,  and  5b.  Ventral,  dorsal,  and  back  views  of  the  type  specimen,  which  consists  of  the  two  valves  united. 
In  figure  5a  the  tmibo  has  been  restored;  on  figure  6  the  ribs  arc  too  much  rounded.     From  Locality 
313g,  Middle  Cambrian  limestone  at  the  south  end  of  the  Timpahute  Range  in  the  Groom  mining  dis- 
trict, Nevada.     V.  S.  Nat.  Mus.  Cat.  No.  52299a. 
338 


U.   S.   GEOLOGICAL  SURVEY 


MONOGRAPH   LI     PL.  CI 


PflANCea  W.ESER  DEL. 


PLATE  CI.  339 

NisusiA  (Jamesella)  amii  Walcott  (p.  731). 

Figures  6,  Ca,  and  6b.  Top,  side,  and  back  views  of  the  type  epecimen,  a  ventral  valve  from  Locality  66a,  Lower 
Cambrian  limestone  bowlder  in  Sillery  conglomerate  on  the  south  shore  of  the  St.  LawTcnce,  4  miles 
(C.4  km.)  below  Quebec,  Canada.    U.  S.  Nat.  Mus.  Cat.  No.  52296. 

Orusia?  eurekensis  (Walcott)  (p.  765). 

Figures  7,  7',  and  7".  Top,  posterior,  and   side  views  of  part  of   mold  of   the  interior  of  a  ventral  valve,  the  type 
specimen.     U.  S.  Nat.  Mus.  Cat.  No.  24596a. 
7a,  7a',  and  7a".  Top,  posterior,  and  side  views  of  a  mold  of  the  interior  of  a  dorsal  valve.     U.  S.  Nat.  Mus. 
Cat.  No.  24596b. 

The  specimens  represented  are  both  from  Locality  65b,  Middle  Cambrian,  top  of  Eldorado  limestone  on  west  side 
of  Secret  Canyon,  Eureka  district,  Nevada.  The  figures  (7  and  7a)  are  redrawn  from  the  specimens  illustrated  by 
Walcott  [1884b,  PI.  IX,  figs.  8a  and  8,  respectively]. 

BiLLINGSELLA    DICE    Walcott  (p.  754). 

Figures  8,  8',  and  8a.  Casts  of  the  interior  of  two  ventral  valves,  with  side  view.     U.   S.  Nat.  Mus.  Cat.  Nos.  52248a 
and  52248b,  respectively.     Figure  8  represents  the  type  specimen. 
8b.  Partial  posterior  view  of  the  matrix  of  a  distorted  ventral  valve.     U.  S.  Nat.  Mus.  Cat.  No.  52248c. 
8c.  Matrix  of  a  distorted  dorsal  valve.     U.  S.  Nat.  Mus.  Cat.  No.  52248d. 
8d.  Cast  of  the  interior  of  a  distorted  dorsal  valve.     V.  S.  Nat.  Mtis.  Cat.  No.  52248e. 

The  specimens  represented  are  all  from.  Locality  319f,  Lower  Ordovician  drift  bowlder  of  sandstone  found  near 
St.  Albans,  Vermont. 

NisusiA  (Jamesella)  argenta  Walcott  (p.  731). 

Figure  9.  Top  and  side  view  of  the  type  specimen,  a  ventral  valve  from  Locality  Ip,  limestones  of  No.  2  of  the  Silver 
Peak  group,  about  2.5  miles  south  of  Barrel  Spring,  Silver  Peak  quadrangle,  Nevada.  U.  S.  Nat.  Mus. 
Cat.  No.  52297a. 

9'.  Posterior  view  of  another  ventral  valve.     The  specimen  from  which  this  was  drawn  can  not  be  located. 

9a  and  9a''.  Top  and  side  views  of  a  ventral  valve  from  Locality  Im,  limestones  of  No.  2  of  the  Silver  Peak 
group,  about  2.5  miles  south  of  Barrel  Spring,  Silver  Peak  quadrangle,  Nevada. 

9b  and  9b'.  Top  and  side  views  of  a  dorsal  valve.     U.  S.  Nat.  Mus.  Cat.  No.  52298b. 

NistisLA  (Jamesella)  utahensis  Walcott  (j).  737). 

Figures  10  and  10a.  Top  and  side  views  of  the  type  specimen,  from  Locality  7w,  Middle  Cambrian  limestone  in  Rock 
Canyon,  in  the  Wasatch  Mountains,  east  of  Provo,  Utah  County,  Utah. 


PLATE  CII. 


341 


PLATE  CII. 

a'.  Anterior  adductor  scars.  sp.  Cast  ofspondyllum. 

a".  Posterior  adductor  soirs.  vs.  Vascular  sinus, 

s.  Median  septum  supporting  spondylium. 

Syntuophia  bakabuensis  (A.  Winchell)  (p.  799). 

Figure  1.  Cast  of  the  interior  of  a  ventral  valve,  showing  the  base  of  the  median  septum  lliat  f<upported  the  spondyl- 
ium, the  cast  of  which  is  clearly  indicated.  Locality  134a,  L'pper  Cambrian  sandstone  in  quaiTy 
1  mile  (1.6  km.)  southeast  of  the  courthouse,  Menouionie,  Dunn  County,  Wisconsin. 

la.  Cast  of  the  interior  of  a  transverse  ventral  valve  associated  with  the  specimen  represented  by  figure  1, 
with  posterior  and  side  outline.     U.  S.  Nat.  Mus.  Cat.  No.  52473b. 

llj.  Top  view  and  side  outline  of  a  cast  of  a  ventral  valve  from  Locality  83,  Upper  Cambrian  sandstone  near 
Trempealeau,  Trempealeau  County,  Wisconsin.  U.  S.  Nat.  Mus.  Cat.  No.  52472a.  The  median 
sinus  is  very  faintly  impressed;  see  figures  Ic  and  Id,  where  it  is  narrower  and  deeper. 

Ic  and  Id.  Top  views  and  side  outlines  of  casts  of  ventral  valves  showing  variatiim  in  form  and  in  the  Ijreadth 
and  depth  of  the  median  sinus.  From  Locality  81o,  Upper  Cambrian  sandstone  below  the  Cliff 
Hotise,  Devils  Lake,  Sauk  County,  Wisconsin.  U.  S.  Nat.  Mus.  Cat.  No.  52474a  and  52474b, 
respectively. 

le  and  Ig.  Top  views  and  side  outlines  of  casts  of  the  interior  of  dorsal  valves,  illustrating  variation  in  form, 
median  fold,  and  cast  of  spondylium.  They  are  associated  with  the  specimen  represented  by  figure 
lb.     U.  S.  Nat.  Mus.  Cat.  Nos.  52472b  and  52472c,  respectively. 

If.  Top  view  and  side  outline  of  a  cast  of  the  interior  of  a  dorsal  valve  associated  with  the  specimen  represented 
by  figure  Ic.  Compare  the  median  fold  and  the  cast  of  the  spondylium  of  this  specimen  with  those  of 
figures  Ic  and  Ig.     U.  S.  Nat.  Mus.  Cat.  No.  52474c. 

Syntrophia  primokdialis  (Wliitfield)  (p.  803). 

Figure  2.  Cast  of  the  interior  of  a  ventral  valve,  showing  cast  of  the  spondylium,  the  supporting  median  septum  and 

large  vascular  sinuses.     U.  S.  Nat.  Mus.  Cat.  No.  52486a. 
2a  and  2b.  Casts  of  the  interior  of  ventral  valves,  illustrating  variation  in   form.     U.  S.  Nat.  Mus.  Cat.  Nos. 

52486b  and  52486c,  respectively. 
2c  and  2c'.  Top  and  side  views  of  cast  of  the  interior  of  a  dorsal  valve.     U.  S.  Nat.  Mus.  Cat.  No.  52486d. 

The  specimens  represented  by  figure|  2,  2a-c  are  from  Locality  99,  Upper  Camlirian  .sandstone  at  Minneiska, 
Minnesota. 

Figures  2d  and  2e.  Side  and  top  views  of  the  type  specimen  of  the  species,  a  dorsal  valve  from  Locality  328k,  Upper- 
Cambrian,  "St.  Croix  sandstone"  at  Roche  ^  Cris  Bluff,  Adams  County,  Wisconsin.  Copied  from 
Whitfield  [1882,  PI.  X,  figs.  1  and  2]. 

Syntrophia  primordialis  argia  AValcott  (p.  804). 

Figure  3.  Cast  of  the  interior  of  a  ventral  valve,  the  type  specimen,  from  Lo<aIity  97,  Upper  Cambrian  sandstone  at 
Reads  Landing,  foot  of  Lake  Pepin,  Wabasha  County,  Minnesota.     U.  S.  Nat.  Mus.  Cat.  No.  52492a. 

Syntrophia  nundina  Walcott  (p.  802). 

Figures  4  and  4'.  Exterior  and  side  views  of  a  ventral  valve  from  Locality  204,  Lower  Ordovician  Pogonip  limestone 

on  eastern  slope  of  ridge  east  of  Hamburg  Ridge,  Eureka  district,  Nevada.     U.  S.  Nat.  Mus.  Cat.  No. 

17281a.    Type  specimen  figured  by  Walcott  [1884b,  PI.  XI,  fig.  7]  as  Triplma  calci/era. 
4a.  Exterior  of  a  dorsal  valve  from  Locality  203,  Lower  Ordovician  Pogonip  limestone  on  ridge  extending 

southwest  from  Wood  Cone,  Eureka  district,  Nevada.     U.  S.  Nat.  Mus.  Cat.  No.  17279a.     Specimen 

figun-d  by  Walcott  [1884b,  PL  XI,  fig.  8]  as  Triplegia  calcifcra. 
4b.  Partly  exfoliated  ventral  valve,  in  which  the  beak  is  either  broken  or  partly  worn  away.     Associated 

with  the  specimen  represented  by  figtire  4a.     I^.  S.  Nat.  Mus.  Cat.  No.  17279b. 
4c.  Castof  the  interior  of  a  ventral  valve,  having  an  unusually  deep  and  strongly  marked  median  sinus.     Ixical- 

ity  201a,  Lower  Ordovician  Pogonip  limestone  on  ea.st  slope  of  ridge  east  of  Hamburg  Ridge,  Eureka 

district,  Nevada.     U.  S.  Nat.  Mus.  Cat.  No.  17280a. 
4d.  Partly  exfoliated  dorsal  valve,  showing  the  cast  of  the  spondylium  and  muscle  scars.     U.  S.  Nat.  Mus. 

Cat.  No.  17491a.     This  specimen  is  doubtfully  referred  to  this  species.     It  is  from  Locality  329a. 

Upper  Cambrian  limestone  on  I'te  Peak,  in  the  \\'asatch  Mountains,  east  of  Cache  Valley,  Cache 

County,  Utah. 
342 


U.  S.   GEOLOGICAL  SURVEY 


MONOGRAPH   L!     PL.  CD 


FRANCES  WIESER  DEc. 


HCLIOTYPE     CO     eOSTOM 


PLATE  CII.  343 

HUENELLA    BILLINGSI    (Walcott)     (p.    806). 

Figure  5.  Casts  of  two  ventral  valves  distorted  by  movement  of  the  matrix  in  wliich  they  were  embedded.     U.  S.  Nat. 

Mus.  Cat.  Nos.  52475a  and  52475b,  respectively. 
5a.  Exterior  of  a  ventral  valve,  the  type  specimen,  showing  the  character  of  the  plications  and  median  sinus. 

U.  S.  Nat.  Mus.  Cat.  No.  52475c. 
5b.  Exterior  of  dorsal  valve,  in  the  same  layer  of  limestone  willi  specimen  represented  l)y  ligure  5a.     U.  S. 

Nat.  Mus.  Cat.  No.  52475d. 
5c.  Exterior  of  dorsal  valve.     U.  S.  Nat.  Mus.  Cat.  No.  52475e. 

The  specimens  represented  are  all  from  Locality  28a,  Middle  ?  Camlirian,  ''St.  Albans  formation'"  1  mile  (1.6  km.) 
east  of  Parker's  quarry,  near  Georgia,  Franklin  County,  Vermont. 

Syntrophia  lateralis  (Wliitfield)  (p.  802). 

[Text  fig.  11,  p.  299.] 

Figure  6.  Partly  exfoliated,  transverse  ventral  valve  and  side  outline.     U.  S.  Nat.  Mus.  Cat.  No.  33447a. 

6a.  Partly  exfoliated,  subquadrate  ventral  valve  and  side  outline.     U.  S.  Nat.  Mus.  Cat.  No.  33447b. 

6b.  Exterior  of  a  transverse  dor.sal  valve.     U.  S.  Nat.  Mus.  Cat.  No.  33447c. 

6c.  Small  young  dorsal  valve  with  only  a  trace  of  the  median  fold.     U.  S.  Nat.  Mus.  Cat.  No.  33447d. 

6d.  Oast  of  interior  of  dorsal  valve,  showing  sides  of  spondylium,  adductor  scars,  and  vascular  sinuses.  U.  S. 
Nat.  Mus.  Cat.  No.  33447e. 

6e.  Posterior  \'iew  of  the  two  valves.     U.  S.  Nat.  Mus.  Cat.  No.  33447f. 

6f.  Portion  of  the  interior  of  the  ventral  valve,  showing  the  complete  spondylium  and  the  division  of  its  sur- 
face into  median  (adductor)  and  lateral  (diductor)  muscular  areas.  X  3.  Copied  from  Hall  and 
Clarke  [1893b,  PI.  LXII,  fig.  9]. 

6g.  Oblique  view  of  the  specimen  represented  in  figure  6f,  showing  the  elevation  of  the  spondylium  and  the 
length  of  its  supporting  median  septum.     Copied  from  Hall  and  Clarke  [1893b,  PI.  LXII.  fig.  10]. 

The  specimens  represented  are  all  from  Locality  227,  Ordoviciau  limestone  near  Fort  Cassin,  Addison  County, 
Vermont. 


PLATE  cm. 


345 


PLATE  cm. 

a'.  Anterior  adductor  impressions.  sp.  Spondyliiim. 

a".  Posterior  adductor  impressions.  s.  Median  .sei)(  urn. 

r.  Diductor  scar.  vs.  Vascular  sinus. 

HUENELLA    TEXANA    (Walcott)     (}).  808). 

Figure  1.  Strongly  costate  ventral  valve,  the  type  specimen.     U.  S.  Nat.  Mus.  Cat.  No.  62494a. 

la.  Ventral  valve  with  well-defined  coatse  in  the  mesial  sinus,  and  nearly  smooth  cardinal  .slopes.     U.  S.  Nat. 

Mus.  Cat.  No.  52494b. 
lb.  Ventral  valve  in  which  there  are  only  slight  traces  of  the  radiating  costse  in  the  mesial  sinu.'i.     U.  S.  Nat. 

Mus.  Cat.  No.  52494c. 
Ic.  Ventral  valve  without  radiating  costae,  with  back  outline.     U.  S.  Nat.  Mus.  Cat.  No.  52494d. 
Id.  Ventral  valve,  with  side  outline,  from  Locality  71,  Upper  Cambrian  limestone  in  Cold  Creek  Canyon, 

Bin-net  County,  Texas.     U.  S.  Nat.  Mus.  Cat.  No.  52495a. 
le.  Dorsal  valve,  with  strong  costse  on  the  median  fold  and  cardinal  slopes.     U.  S.  Nat.  Mus.  Cat.  No.  52494e. 
If.  Dorsal  valve,  with  fine  radiating  costs.     U.  S.  Nat.  Mus.  Cat.  No.  52494f. 
Ig.  Dorsal  valve,  having  median  fold  with  well-marked  costae  and  smooth  cardinal  -slopes,  with  back  outline 

of  the  same.     U.  S.  Nat.  Mus.  Cat.  No.  52494g. 
Ih.  Oblique  section  of  spondylium  of  ventral  valve  a  short  distance  from  the  apex.     V.  S.  Nat.  Mus.  Cat. 

No.  52494h. 
li.  Section  of  dorsal  valve  cutting  across  the  spondylium.     U.  S.  Nat.  Mus.  Cat.  No.  524941. 

With  the  exception  of  figiu-e  Id,  all  the  specimens  represented  arc  from  Locality  68.  Upper  Cambrian  limestone, 
in  Packsaddle  Mountain,  Llano  County,  Texas. 

HUENELLA    ABNORMIS    (Walcott)     (p.  805). 
[Text  fig.  13,  p.  299.1 

Figure  2.  Ventral  valve  with  .strong  radiating  costse.     U.  S.  Nat.  Mus.  Cat.  No.  52462a. 

2a  and  2a'.  Exterior  and  side  views  of  ventral  valve,  the  type  specimen,  with  radiating  costae  in  the  mesial 

sinus.     U.  S.  Nat.  Mus.  Cat.  No.  52462b. 
2b.  Cast  of  interior  of  ventral  valve,  showing  cast  of  spondylium,  main  vascular  canals,  and  muscle  scars. 

U.  S.  Nat.  Mus.  Cat.  No.  52462c. 
2c.  Dorsal  valve  with  prominent  median  fold,  from  Locality  158,  L^pper  Cambrian  limestone  north  of  East 

Gallatin  River,  near  Hillsdale,  Threeforks  quadrangle  (U.  S.  Geol.  Survey),  Gallatin  County,  Mon- 
tana.    U.  S.  Nat.  Mus.  Cat.  No.  52461a. 
2d  and  2d'.  Top  and  side  view  of  nearly  smooth  dorsal  valve.     U.  S.  Nat.  Mus.  Cat.  No.  52462d. 
2e.  Dorsal  valve  with  several  plications  on  median  fold.     U.  S.  Nat.  Mus.  Cat.  No.  52462e. 
2f.  Interior  of  dorsal  valve  showing  muscle  scars  and  vascular  markings.     U.  S.  Nat.  Mus.  Cat.  No.  52462f. 
2g.  Posterior  view  of  a  ventral  valve  showing  area.     U.  S.  Nat.  Mus.  Cat.  No.  o2462g. 
2h.  Partial  cast  of  interior  of  dorsal  valve.     U.  S.  Nat.  Mus.  Cat.  No.  524G2h. 
2i.  Interior  of  a  dorsal  valve  in  which  the  muscle  scars  and  spondylium  (cruralium)  have  been  more  or  le.ss 

eroded.     U.  S.  Nat.  Mus.  Cat.  No.  524621. 
2j.  Cast  of  the  interior  of  a  dorsal  valve,  showing  strong  muscle  scars  and  radiating  costse  on  the  mesial  fold. 

This  specimen  is  associated  with  the  shell  represented  by  figure  2c.     L'.  S.  Nat.  Mus.  Cat.  No.  52461b. 
2k.  Cast  of  the  interior  of  a  dorsal  valve,  .showing  radiating  ^'ascular  canals  at  the  top  of  the  cast  of  four  strong 

costae.     ThLs  specimen  is  a.ssociated  with  the  shell  represented  by  figure  2c.     L'.  S.  Nat.  Mus.  Cat. 

No.  52461c. 
21  and  2m.  Sections  of  ventral  and  dorsal  valves  cut  across  the  imibo  to  show  sections  of  the  spondylium  in 

each  valve.     U.  S.  Nat.  Mus.  Cat.  Nos.  52462J  and  52462k,  respectively. 

With  the  exception  of  figures  2c,  2j,  and  2k,  the  specimens  rei>resented  by  figures  2.  2a-in  are  from  Locality  4j, 
Middle  Cambrian  limestone  at  the  head  of  Deep  Creek,   Canyon  quadrangle  (V .   S.  Geol.   Survey),  Yellowstone 
National  Park,  Wyoming. 
346 


MONOGRAPH   LI     PL.  CHI 


U.  S.   GEOLOGICAL  SURVEY 


FRANCES  V.tESER  Dfl. 


HtLlOTVPE    CO   BOSTON 


PLATE  cm.  347 

Syntrophia  alata  Walcott  (p.  799). 

Figures   3,  3',  and  3".  Cast  of  the  interior  of  a  ventral  valve,  with  side  and  back  views.     U.  S.  Nat.  Mus.  Cat. 
No.  52466a. 
3a.  Exterior  of  ventral  valve,  the  type  specimen.     U.  S.  Nat.  Mu.s.  Cat.  No.  52466b. 

3b  and  3c.  Casts  of  interior  of  ventral  valves.     U.  S.  Nat.  Mus.  Cat.  Nos.  52466c  and  52466d,  respectively. 
3d.  Partial  cast  of  the  interior  of  a  dorsal  valve.     U.  S.  Nat.  Mus.  Cat.  No.  52466f. 

The  specimens  represented  by  figures  3,  3a-d  are  all  from  Locality  69.  Tapper  Cambrian  limestone  near  Honey 
Creek,  Burnet  County,  Texas. 

Syntrophia  rotundata  Walcott  (]>.  804). 

Figures  4,  4';  4a;  and  4b,  4b'.  Top  and  side  views  of  three  dorsal  valves  varying  in  form  and  in  strength  of  median 
fold.     U.  S.  Nat.  Mus.  Cat.  Nos.  52493a,  52493b,  and  52493c,  respectively. 

4a'.  View  of  area  and  hinge  line  of  ventral  valve.     U.  S.  Nat.  Mus.  Cat.  No.  52493h. 

4c  and  4c'.  Top  and  side  views  of  ventral  valve,  the  type  specimen.  V.  S.  Nat.  Mus.  Cat.  No.  52493d. 
Another  specimen  (Cat.  No.  52493g)  was  used  to  restore  certain  portions  of  this  figure. 

4d.  Section  across  the  umbo  of  a  ventral  valve,  showing  outline  of  section  of  spondylium.  IT.  S.  Nat.  Mus. 
Cat.  No.  52493e. 

4e.  Section  of  shell  and  spondylium  of  dorsal  valve.     U.  S.  Nat.  Mus.  Cat.  No.  52493f. 

The  specimens  represented  by  figures  4,  4a-e  are  all  from  Locality  14k.  LTpper  Cambrian  limestone  on  Wolf 
Creek,  15  miles  (24.2  km.)  west-southwest  of  Sheridan,  Bighorn  Mountains,  Wyoming. 


PLATE  CIV. 


349 


PLATE  CIV. 

cl.  Area  of  attachment  of  posterior  muscles.  nc.  Umbonal  cavity, 

h.  Central  scars.  vs.  Main  vascular  sinuses, 

sp.  Cast  of  spondyliuni. 

Syntrophia  calcifera  (Billings)  ({>.  800). 

Figure  1.  Ventral  valve.-probably  the  one  represented  by  figure  Ic.     Copied  from  Billings  [1861a,  fig.  3a,  p.  319]. 

la.  Dorsal  valve,  possibly  the  one  represented  by  figure  le.     Copied  from  Billings  [1861a,  fig.  3b,  p.  319]. 

lb.  Cast  of  a  ventral  valve  showing  spondylium.    Copied  from  Billings  [1861a,  fig.  3c,  p.  319]. 

Ic  and  Ic'.  Top  and  side  views  of  ventral  valve,  from  Locality  392j,  Lower  Ordovician  limestone  at  Point 
Levis,  Province  of  Quebec,  Canada.  Geol.  Survey  Canada.  In  all  probability  this  is  the  specimen 
used  by  Billings  in  drawing  his  figure  3a  [1861a,  p.  319].     It  may  be  taken  as  the  type. 

Id.  Ventral  valve  with  gently  rounded  shallow  sinus,  with  a  large  projection  to  fit  in  the  fold  of  the  dorsal  valve. 
It  is  associated  with  the  specimen  represented  by  figure  Ic.     Gcol.  Survey  Canada. 

le  and  le'.  Top  and  side  views  6i  a  dorsal  valve  from  Locality  3921,  Lower  Ordo\'ician  limestones  at 
Phillipsburg,  Province  of  Quebec.  Geol.  Survey  Canada.  The  specimen  represented  by  figure  le  is 
possibly  the  one  used  by  Billings  in  drawing  his  figure  3b  [1861a,  p.  319]. 

If.  Ventral  valve  with  side  outline.     U.  S.  Nat.  Mus.  Cat.  No.  52476a. 

Ig  and  Ih.  Top  and  side  \-iew  of  a  ventral  valve.     U.  S.  Nat.  Mus.  Cat.  No.  52476b. 

li.  A  smooth  dorsal  valve,  doubtfully  referred  to  this  species.     U.  S.  Nat.  Mus.  Cat.  No.  52476c. 

The  specimens  represented  by  figures  If-i  are  from  Locality  392],  Lower  Ordovician  limestones  at  Point  Levis, 
Province  of  Quebec,  Canada. 

Clarkella  montanensis  (Walcott)  (]>.  810). 

Figures  2  and  2'.  Top  and  back  view  of  a  broken  ventral  valve.     U.  S.  Nat.  Mus.  Cat.  No.  11587a. 

2a  and  2a'.  Top  and  side  view  of  a  rhomboidal  dor.sal  valve,  the  type  specimen.     U.  S.  Nat.  Mus.  Cat.  No. 

11587b. 
2b.  Transverse  dorsal  valve.     U.  S.  Nat.  Mus.  Cat.  No.  11587c. 
2c  and  2d.  Sections  across  the  umbo  of  two  ventral  valves,  showing  sections  of  the  septa  supporting  the 

spondylium.     U.  S.  Nat.  Mus.  Cat.  Nos.  11587d  and  11587e,  respectively. 

The  specimens  represented  are  all  from  Locality  302j,  Ordovician  limestone  east  of  West   Gallatin  (Gallatin) 
River,  above  Gallatin,  Gallatin  County,  Montana. 

Huenella  orientalis  (Walcott)  (p.  808). 

Figure  3.  Top  and  side  views  of  a  ventral  valve,  the  type  specimen.     U.  S.  Nat.  Mus.  Cat.  No.  52564a. 
3a.  Top  and  side  views  of  an  exfoliated  dorsal  valve.     LT.  S.  Nat.  Mus.  Cat.  No.  52564b. 
3b.  Partly  exfoliated  dorsal  valve.     U.  S.  Nat.  Mus.  Cat.  No.  52564c. 

The  specimens  represented  are  all  from  Locality  C64,  Upper  Cambrian  limestone  2.7  miles  (4.4  km.)  southwest  of 

Yenchuang,  Sintai  district,  Shantung,  China. 

/ 

Syntrophia  ortiiia  Walcott  (p.  803). 

Figure  4.  Ventral  valve,  the  type  (specimen,  from  Locality  C56,  Upper  Cambrian  Chaumitien  limestone  at  Pagoda 

Hill,  1  mile  (1.6  km.)  west  of  Tsinan,  Shantung,  China.     U.  S.  Nat.  Mus.  Cat.  No.  52562a. 
4a  and  4a'.  Exterior  of  ventral  valve,  with  side  outline,  from  Locality  C64,  ri)per  Cambrian  limestone  2.7  miles 

(4.4  km.)  southwest  of   Yenchuang,  Sintai  district.  Shantung,  China.     U.  S.   Nat.  Mus.  Cat.  No. 

52563a. 
4b  and  4b'.  Top  and  side  views  of  a  dorsal  valve  from  Locality  C54,  Upper  Cambrian  Chaumitien  limestone 

0.66  mile  (1.1  km.)  west  of  Tsinan,  Shantung,  China.     U.  S.  Nat.  Mus.  Cat.  No.  52561a. 

SWANTONIA    ANTIQUATA   (BilUngs)    (p.  797). 

Figures  5,  5a,  and  5b.  Top,  side,  and  back  views  of  the  cast  of  a  ventral  valve  from  Locality  319e,  Lower  Cambrian 
sandy  shales  about  2  miles  (3.2  km.)  east  of  Swanton,  Franklin  County,  Vermont.  V.  S.  Nat.  Mus. 
Cat.  No.  15363a.     This  specimen  was  figured  by  Walcott  [llSSOb,  PI.  VII,  fig.  8]  as  Camarella  aniiquala. 

350 


U.  S.  GEOLOGICAL  SURVEY 


MONOGRAPH  LI     PL.  CIV 


..^:M^=^ 


7a' 


FRANCES  WIESER  OEL. 


LIOTVPE    CO   OOSTOI. 


PLATE  CIV.  351 

SWANTONIA    WEEKSI  Walcott  (p.   797). 

Figure  6.  Top  view  of  an  imperfect  ventral  valve,  the  type  specimen,  from  Locality  Iv,  Lower  Cambrian  shales  of 
No.  3  of  the  Silver  Peak  group,  3  miles  north  of  Valcalda  Spring  and  4  miles  northwest  of  the  Drink- 
water  mine,  Esmeralda  County,  Nevada.     U.  S.  Nat.  Mus.  Cat.  No.  52500a. 

QuEBECiA  CIRCE  (Billings)  (p.  610). 

Figure  7.  Cast  of  interior  of  ventral  valve,  showing  outline  of  main  vascular  sinu.ses  and  cardinal  muscle  scars.     U.  S. 

Nat.  Mus.  Cat.  No.  14892a. 
7a  and  7a'.  Back  and  side  views  of  specimen  represented  by  figure  7.     U.  S.  Nat.  Mus.  Cat.  No.  14892a. 
7b.  Back  view  of  the  cast  of  a  ventral  valve,  in  which  the  cardinal  scars  are  large  and  strongly  defined.    The 

specimen  from  which  this  figure  was  drawn  can  not  be  located. 
7c.  Cast  of  the  interior  of  a  dorsal  valve.     IT.  S.  Nat.  Mus.  Cat.  No.  14892c. 
7d.  Artificial  cast  of  the  interior  of  a  dorsal  valve.     The  original  specimen  can  not  be  located.     U.  S.  Nat. 

Mus.  Cat.  No.  14892f. 
7e.  Artificial  cast  taken  from   the  artificial  cast  shown    by  figure  7d.     U.  S.  Nat.  Mus.    Cat.  No.  14892e. 

Specimen  figured  by  Walcott  [1886b,  PI.  X,  fig.  3a]. 
7f.  Cast  of  the  interior  of  a  dorsal  valve.     U.  S.  Nat.  Mus.  Cat.  No.  14892b. 
7g.  Cast  of  the  interior  of  a  dorsal  valve  which  is  old  and  thick  .shelled.     U.  S.  Nat.  Mus.  Cat.  No.  14892d. 

The  specimens  represented  are  all  from  Locality  3191,  Lower  Cambrian  limestone  bowlders  in  conglomerate  at 
Trois  Pistoles,  on  St.  Lawrence  River  below  Quebec,  Canada. 


INDEX  TO  PART  11, 


Note.— This  index  includes  also  reference  to  species  figured  in  Part  I  (text  figures),  and  all  page  references  are  to  that  part.  In  order  to  make 
the  figured  species  easily  accessible  to  one  not  familiar  with  the  numerous  changes  in  the  generic  references  the  entries  are  arranged  alphabetically 
by  genera,  subgenera,  species,  and  varieties.  Roman  numerals  refer  to  plates,  arable  numerals  to  the  figures  on  the  plates.  The  index  to  Part  I 
includes  the  plate  and  figure  reference  of  each  of  the  type  specimens  figured  in  the  monograph. 


abnormis  [HuenellaJ,  (Walcott ) CIII:  2, 2a-m; 

Text  fig.  13,  p.  299. 

acadicus  [Oboius],  Walcott XI;  5. 

(Acritis)  antiquissunus  [Oboius],  (Eichwald) XIII:  3; 

XV:2,  2a-d. 

(Acritis?)  rugatus  [Oboius],  Walcott XXII:  2 and  3. 

Acrothele  artemis  Walcott Text  fig.  54,  p.  634. 

avia  Matthew LXI:  7, 7a-b: 

LXII:l,la-k. 

avia  puteis  Matthew Not  figured. 

bellapunctata  Walcott L\'II:  3, 3a-b. 

bellula  Walcott LVIII:  5, 5a-h. 

bergeroni  Walcott LVIII:  6, 6a-c. 

bohemiea  ( Barrande) LVII;  1,  la-d. 

borgholmensis  Walcott LXIII:  2, 2a-b. 

ceratopygarum  (Brogger) LXIII:  1,  la-c. 

colleni  Walcott LXIII:  6, 6a-b; 

Text    figs.    55A-E, 
p.  641. 

coriacea  Linnarsson LVI:  1 ,  la-i. 

decipiens  Walcott LVIII:  3,3a-d. 

diehotoma  Walcott LX:  2. 

gamagei  (Hobbs) LX:  5, 5a-c. 

intermedia  Linnarsson LVI:  3, 3a-d. 

levisensis  Walcott LXXXI:  12, 12a-b. 

maculata  (Salter) LVII:  2, 2a-b; 

LVIII:  2. 

matthewl  (Hartt) LXI:  1, la-g. 

matthewieryx  Walcott LXI:  2. 

matthewi  lata  Matthew LXI:  3. 

matthewi  multicostata  Matthew LXI:  5, 5a-c. 

?  minuta  Walcott .' LXIII;  3. 

nitida  (Ford) LVIII:  4, 4a. 

panderi  Walcott LIX:  S,  5a-c. 

pretiosa  ( Billings) LVIII:  1 ,  la-g. 

prima  (Matthew) LXI:6, Oa-b; 

LXII;  2. 

prima  costata  (Matthew) LXI:  4, 4a-d. 

primiBva  (de  Verneuil  and  Barrande) LVII:  6. 

proles  Matthew LXII:  3, 3a-e;  4, 4a, 

quadrilineata  Pompeckj LVII:  5. 

rara  Walcott LXIII:  4, 4a. 

spurri  Walcott LX:  3. 3a-c. 

subsidua  (White) LX:  l,la-o;  8. 

subsiduahera  Walcott LX:  9. 

subsidua  Iwvis  Walcott Not  figured. 

turaeri  Walcott LX:  7,  Ta. 

villahoimensis  Delgado Not  figured. 

woodworthi  Walcott LX:  G. 

yorkensis  Walcott LIX:4, 4a-b. 

sp.  undt.  Moberg Not  figured. 

sp.  undt.  Walcott LXIII:  5. 

Acrothele  (Redlichella)  granulata  (Linnarsson) LVI:  2,2a-n. 

Acrothyra  minor  Walcott LXXVI:  4, 4a-b; 

Text  fig.  59,  p.  717. 

proa  via  (Matthew) LXX  V:  3; 

LXXVI:3,3a-u. 

sera  (Matthew) LXXX:  4,4a-c;   5, 

5a-d;   6,6a-i;    7, 
7a-b;  8?. 

signata  Matthew LXXX :  1 ,  la-d . 

signata  orta  Matthew LXXX:  3. 3a-b. 

signata  prima  Matthew LXXX:  2, 2a-b. 


62667°— VOL  51,  pt  2—12- 


-23 


Acrotreta  argenta  Walcott LXVII:  5,  oa-g. 

attenuata  Meek LXPV:  1,  la-o; 

LXXIX:  6,6a. 

attenuata  var.  Walcott LXV:  2. 

babel  Barrande LXXVII:  6, 6a-b. 

baileyi  Matthew LXXVII:  2, 2a-d. 

bellatula  Walcott LXXVIII:  4, 4a-d. 

belti  (Davidson) LXXVII:  8, 8a. 

bisecta  Matthew LXVI:  7,7a~e. 

??  cancellata  Walcott LXXIX:  5,  Sa. 

carinata  (Scgerberg  MS.)  Moberg  and  Segcr- 

herg Text  figs.  06A-D, 

p.  689. 
circularis  Moberg  and  Scgerberg Text  figs.  57A-C, 

p.  680. 

claytoni  Walcott LXXIV:  3, 3a-b. 

concentrica  Walcott LXXVII:  1,  la-b. 

conula  Walcott LXXV:  2. 2a-b. 

convcxa  Walcott LXVI:  6, 6a-c. 

curvata  Walcott LX VIII:  1 ,  la-n. 

definita  Walcott LXIV:    2,2a-g,    3, 

3a-b, 

depressa  (Walcott) LXVI:  8, 8a-c. 

eggegrundensis  Wunan LXX:  2a-d. 

emmonsi  Walcott LXV:  6. 

germna  Billings LXVI:  1,  la-b. 

gemmula  Matthew LXVI:  3, 3a-c; 

LXXVII:  5,5a-f. 

gracia  Walcott LXVI:  5, 5a-d. 

idahoensis  Walcott LXV:  1,  la-i; 

LXVIII:  2,2a-g. 

cf.  idahoensis  Walcott Not  figured. 

idahoensis  alta  Walcott LXV;  4,4a-b. 

idahoensis  sulcata  Walcott LXV;  5. 

inchoans  (Barrande) XV:  7, 7a. 

inflata  (Matthew) LXXVI:  l,la-k;  2, 

2a. 

loitorgai  Walcott LXV:  3,  3a-e,  g-k; 

Text  fig.  58,  p.  692. 

lisani  Walcott LXVIII:  3,3a-c. 

marjumensis  Walcott LXXVIII:   2,  2a^d. 

microscopica  (Shumard) LXVII:  I,  la-h,  lo; 

2, 2a-d. 

microscopica  missouriensis  Walcott LXVII:  4, 4a-b. 

microscopica  tetonensis  Walcott LXVII:  3, 3a-d. 

7  minima  ( Barrande) LXXVII:  7, 7a. 

mlsera  ( Billings) LXXII:  2, 2a-l. 

neboensis  Walcott LXXVII:  9, 9a-b. 

nicholsoni  Davidson LXXIII:  1,  la-k;6, 

6a-b. 

nox  Walcott LXXVII;  10. 

oelandica  Westergird Not  figured. 

ophirensis  Walcott LXXIV:  1,  la-p. 

ophirensis  descendens  Walcott LXXVIII:  1,  la-c. 

opliirensis  rugosa  Walcott LXXIV;  2,  2a-e. 

ovalis  Walcott LXVI:  2,  2a-b. 

pacifica  Walcott LXIX:  6,  6a-e. 

pari-ula  (Wallerius) LXXVII;  4,  4a. 

prim^eva  Walcott LXIX:  1,  la-f. 

pyxidicula  White LXIX:   2,  2a-f;  3, 

3a-f. 

rudis  Walcott LXV;  3f; 

LXXV:  1. 

353 


354 


CAMBKIAN  BRACHIOPODA. 


Aerotrcta  sabrinae  (Callaway) LXXIII:  5,  5a-d. 

sagittalis  (Salter) LXXI:  2,  2a-h;  3, 

3a-j. 

cf.  sagittalis Not  figured. 

sagittalis  magna  (Matthew) LXVI:  4,  4a-f. 

sagittalis  taconica  ( Walcott ) LXXI:  1,  la-o. 

sagittalis  transversa  (Uartt) LXXII:  1,  la-k. 

sctimalenseei  Walcott LXX :  1,  la-s. 

seebachi  Walcott LXX  VII:  3,  3a. 

shantungensis  Walcott LXIX:  5,  5a-e. 

signalis  Walcott LXIX:  4. 

socialis  von  Seebach LXXIII:  3,  3a--c;  4, 

4a-e. 

spinosa  Walcott LXXIX:  4,  4a-g. 

subconica  Kutorga LXXIII:  2,  2a^i. 

ulrichi  Walcott LXX VIII:  3. 

uplandica  Wiman LXX:  3,  3a-c. 

uplandica  limoensis  (Wiraan) LXX:  4,  4a-c. 

sp.  undt.  Walcott Not  figured. . 

sp.  undt.  Wcstergard Not  figured. 

acuminata  [Lingulella  (Lingulepis)],  (Conrad) XXXIV:  3, 3a-c; 

XL:  1,  la-s; 
XLI:  1,  la-n; 
XLII:  1,  la-o. 
acuminata  meeki  [Lingulella  (Lingulepis)),  (Wal- 
cott)  XLI:  2,2a. 

acuminata  sequens  [Lingulella  (Lingulepis)),  Wal- 
cott  Te.xt  figs.   46.\-B, 

p.  551. 

acuminatus  [Obolus  (Scbmidtia)],  Mickwitz XIV:  2,  2a-c. 

acutangula  [Lingulella),  (Roemer) XVII:  1,  la-o. 

advenus[Obolus?),  Barrandc XII:  5,  5a-b. 

affinis  [OboUis  (Lingulobolu.s)),  (Billings) XVI:  1,  la-e. 

agnostorum  [Lingulella],  (Wallerius) XXX:  15. 

agreste  [Eoorthis],  (Walcott) LXXXIX:  6,  6a. 

alabamaensis  [Micromitra] ,  (Walcott) II:  5,  5a-c. 

Wandensis  [Obolus  (Westonia)),  Walcott XLVIII:  6,  6a. 

alata  [Syntrophia),  Walcott CIII:  3,  3a-d. 

alberta  [.\isusia),  (Walcott) C:  3,  3a-d. 

alta  [.\crotreta  idahoensis),  Walcott LXV:  4,  4a-b. 

ambigua  [Elkania),  (Walcott) LI:  2,  2a-c. 

amii  [Nisusia  (Jamesella)),  Walcott CI:  6,  6a-b. 

ampla  [Lingulella),  (Owen) XXVIII:  1,  la-j. 

anatina  [Lingula],  Bruguidre Text  figs.  34C-D, 

p.  374. 

anceps  [Obolus),  Walcott X:  3,  3a-f. 

ancillus [Obolus ?),  (Barrandc) XII:  2. 

anomala  [ Wimanella  ?),  (Walcott) LXXXVII:  1,  la-e. 

antiquata  [Swantonia),  (Billings) CIV:  5,  5a-b. 

antiquissimus  [Obolus  (.\critis)),  (Eichwald) XIII:  3; 

XV:  2.2a-d. 

apollinis  [Obolus],  Eichwald VII:  1-8,  10-17; 

XIV:  6,  6a; 
Text  figs.  4  and  15, 
p.  299. 

apollinis  ingricus  [Obolus],  Eichwald Not  figured. 

apollinis  maxim  us  [Obolus],  Mickwitz VII:  9; 

XIV:  7. 7a. 

apollinis  quenstedti  [Obolus],  (Mickwitz) Text  figs.34A-B,p. 

374. 

appalacliia  [Billmgsella?],  Walcott LXXXVII:  2, 2a-b. 

appalachia  [DiccUomus],  Walcott LIU:  4, 4a-g. 

argenta  [  Acrotreta],  Walcott LX VII:  5, 5a-g. 

argenta  [Nisusia  (Jamesella)],  Walcott CI:  9.9a-b. 

argla  [Syntrophia  primordialis],  Walcott CII:  3. 

arguta  [Lingulella],  (Walcott) XXIV:  5. Sa-b. 

artemis  [  Acrothele],  Walcott Text  fig.  54,  p.  634. 

asiatica  [Obolella],  Walcott LV:  0.  Oa. 

atava  [Lingulella],  (Matthew) XXXV:  5. 5a-h. 

atava [Eoorthis],  (Matthew) XCV: 7, 7a-b. 

atava  insula;  (Lingulella).  (Matthew) XXXV:  .s,  Xa. 

atlantica  [Obolella],  Walcott LV:  la-  < 

Text  fig.  51,  p.  590. 

atrMJOides  [Orusia  Icnticularis],  (Matthew) XCVIII:  5. 

attenuata  [Acrotreta],  Meek LXIV:  l.la-o; 

LXXIX:  6,6a. 

attenuata  var.  [Acrotreta],  Walcott LXV:  2. 

auga  [Lingulella],  (Walcott) XXIV:6.6a-g. 

aurora  [Obolus  (Westonia)],  (Hall) XLVI:  1,  la-h. 


avia  [Acrothele),  Matthew LXI:  7,7a-b; 

LXII:  l.la-k. 

aviaputeis  [Acrothele),  Matthew Not  figured. 

babel  [.\crotreta],  Barrandc LX X  VII;  6, 6a-b. 

baileyi  (Acrotreta],  Matthew L.KX  VII:  2, 2a-d. 

baltieus  [obolus  (Westonia)),  Walcott XLVIII: 7, 7a-b. 

barabuensis  [.Syntrophia],  (A.  Winchell) CII:  l,la-g. 

?  barrandel(liots(ordial,  Walcott LVII:  7,7a-b. 

bavarica  [Eoorthis),  (Barrande) XCVII:  4. 

bavaricus  (Obolus?),  ( Barrande) XV;  10, 10a. 

bella  (Lingulella),  (Walcott) XIX:  2,2a-q; 

X.XXVI:  4. 

bella  [Micromitra  (Paterina)),  (Billings) II:  l,la-c. 

bellapunctata  (Acrothele),  Walcott LVII:  3, 3a-b. 

bellatula  (.\crotrela),  Walcott LXX  VIII:  4,4a-d. 

belli [Oljolus],  (Billings) XXXVIII:3,3a-b. 

bellula  [Acrothele),  Walcott LVIII:  5, 5a-h. 

bellula  (Lingulella),  (Walcott) XIX:  1,  la-e. 

bellulus  (Obolus  (Fordinia)],  (Walcott) LI:3,3a-f. 

belli  l-'Vcrotrcta),  (Davidson) LXX\TI:  8, 8a. 

bergeroni  [.\crotheIe],  Walcott LVIII:  6, 6a-c. 

Bicia  gemma  ( Billings) L:  1,  la-n. 

whiteavesi  Walcott L:  2. 2a-c. 

Billmgsella?  appalachia  Walcott LXXXVII:  2, 2a-b. 

bivia  Walcott Text  figs.  65A-C,  p. 

750. 

coloradoensis  (Shumard) LXXXV:  1,  la-z; 

Text  figs.  5,  p.  299, 
and  06,  p.  751 . 

dice  Walcott CI:  8. 8a-d. 

exporrecta  (Linnarsson) LXXXVIII:l.la-l. 

exporrecta    rugosicostata  Walcott LXXXVIII:2,2a-c. 

hicksi  (.Salter  MS.)  (Davidson) XCVII:  7,  7a-b. 

highlandensis  (Walcott) .LXXXVII:  4,4a-c. 

lindstromi  (Linnarsson) LXXXVII:  6, 6a-f. 

major  Walcott LXXXVI;  1,  la. 

marion  \\'alcott Text    figs.    67A-B, 

p.  758. 

obscura  Walcott LXX XVI:  G. 

orientalis  (Whitfield) LXXXVI:  2, 2a-b. 

plicatella  Walcott LXXXVI:  3,  3a-n; 

Text  fig.  1,  p.  299. 

piimpeliyi  Walcott XCVII:  8,  8a-c. 

retrodexa  (Matthew) XC:  1,  la-h. 

richthofeni  Walcott LXXXIX:  1. 

romingeri  (Barrande) XC:  2,  2a-n. 

salemensis  (Walcott) LXXXVII:  3, .3a. 

striata  Walcott LXXXVI:  4,  4a-c. 

whitfieldi  (Walcott) LXXXVI:  5,  5a. 

billingsi  (Huenella),  (Walcott) CII:  S,  5a-c. 

billingsi  [Protorthisl,  (Hartt) XCIX:  1,  la-g. 

billingsiana  [Lingulella).  (Whitcavcs) XXIX:  3,3a. 

bisecta  [.\crotreta),  Matthew XLVI:  7,  7a-e. 

bivia  [Billingsella),  Walcott Text    figs.    65A-C, 

p.  750. 

blackweldcri  [Obolus  (Westonia))  Walcott XXXIX:  10,  XOa-c. 

bohemica  [Acrothele],  ( Barrande) LVII:  1,  la-d. 

borgholmensis  [Acrothele],  Walcott LXIII:  2,  2a-b. 

bornemanni  [Lingulella),  (Walcott) XXX:  18, 18a-c. 

Botsfordia?  barrandei  Walcott LVII:  7,  7a-b. 

c:rlata  (Hall) LIX:l,la-q;3,3a-b. 

granulata  (Redlieh) LVII:  4,  4a-r. 

pulchra  (Matthew) I.XII:  5,  5a-l. 

bottnicns  [Obolu.s  (Westonia)],  (Wiman) XLVIII:  4.  4a-c. 

bretonensis  [Obolus  ( rahrobolus)),  (Matthew) XXXII:  5,  5a-g. 

bretonensis  lens  [Obolus  (I'ahi'obolus)),  (Matthew).  Not  figured. 

(Brbggeria)salteri  [Obolus],  (lloll) XIII:  1,  la-n; 

XV:  4,  4a-il. 

buchi  [Keyserlingia],  (de  Verneoil) LXXXI:  4,  4a-e. 

buttsi  [Lingulella),  Wahott XXIX:  4,  4a-b. 

Ciclata  [Botsfordia),  (Hall) LIX:    1,    la-q;    3, 

3a-b. 

calcilera  [Syntrophia),  (Billings) CIV:  1,  la-i. 

Cambria  (Schuchertiua),  Walcott LI:  6,  Oa-m. 

Cambria  [Syntrophia],  Walcott Text    figs.    72A-D, 

p.  800. 

campbelli  (Syntrophia),  Walcott Text    figs.    73A-F, 

p.  801. 

cancellata  [Acrotreta??),  Walcott LXXIX:  5, 5a. 

cania  [Lingulella),  (Walcott) XXXA':  3, 3a-d. 


INDEX. 


355 


cariuata  [Acrotreta],  (Segerberg  MS.)  Moberg  and 

Segerberg Text     figs.    56A-D, 

p.  680. 

cedens  [Lingulella],  (Barrande) XXX:  8. 

celatus[ObolLi3(Scliiaidtia)],  (Volborth) XIV:  1,  la-c. 

ceratopygaruin  [Acrothele],  (Brogger) LXIII;  1,  la-c. 

chinensLs[Obolusl,  (Walcott) XXXIX:  7,  7a-b. 

christianise  [EoorthisJ,  (Kjerulf) XCV:  1,  la-h. 

chromatica[OboIella),  Billings LIV:  1,  la-i. 

chuarensis  [Obolus  (Westonia)],  (Walcott) XXV:  2,  2a-«. 

ciugulata[KutorginaJ,  (Billings) V:  1,  la-s; 

Text  flgs.  3  and  8, 

p.  299,  and  50A-C, 

p.  581. 

Circe  [Quebecia],  (Billings) CIV:  7,  7a-g. 

circularis  [.\crotreta],  Moberg  and  Segerberg Text    figs.    57 A-C^ 

p.  680. 
clarkei  [Lingulella],  Walcott Te.xt    figs.    42A-D, 

p.  486. 

Clarkella  montanensis  ( W  alcott) CIV:  2,  2a-d. 

clarki  [Dearbomia],  Walcott LXXXII:  7,  7a-d. 

claytoni  [Aerotreta],  Walcott LXXIV:  3,  3a-b. 

coUeni  [.\crotheleJ,  Walcott LXIII:  6,  6a-b; 

Text  figs.  55A-E,  p. 

641. 
collicia  [Lingulella],  (Matthew) XXXV:   1,  la-I:   2, 

2a-d. 

coloradoensis  [Billingsella],  (Shumard) LXXXV:  1,  la-z; 

Text  flgs.  5,  p.  299, 

and  66,  p.  751 . 

Columbiana  [Philhedra],  (Walcott) LXXXI:  10. 

complexus  [Obolus],  Barrande XII:  3,  3a;  S,  8a. 

compta  [Nisusia],  (Tate) XCVII:  14. 

concentrica  [.\crotreta],  Walcott LXX  VII:  1,  la-b. 

concinna  [Lingulella],  Matthew XXXIII:  2,  2a~h: 

XXXIV:  1,  la-r. 

contraria[Orbiculoidea],  (Barrande) LXXXI:  9. 

conula  [Acrotreta],  Walcott LXXV:  2,  2a-b. 

convexa  [Acrotreta],  Walcott LX  VI:  6,  6a-c. 

convexa  [Lingulella  winona],  (Walcott) XVIII:  4,  4a-d. 

coriacea  [Acrothele],  Linnarsson LVI:  1,  la-i. 

corrugata  [Finkelnburgia  osceola],  (Walcott) Not  figured. 

costata  [Acrothele  prima],  (Matthew) LXI:  4,  4a-d. 

crassa  [Obolella],  (Hall) LIV:  2,  2a-n; 

Text  fig.  14,  p.  299. 

crassa  elongata  [Obolella],  Walcott LV:  5,  5a. 

crassus  [Obolus  (Schmidtia)],  Mickwitz XIV:  4,  4a-d. 

crenistria  [Micromitra  (Paterina)],  (Walcott) Ill:  4,  4a-b. 

cuneola  [Lingulella],  (Whitfield) XXVII:  7,  7a-b. 

Curticia  elegantula  Walcott I:  2,  2a-l. 

curvata  [.Vcrotreta],  Walcott LX  VIII:  1,  Ian. 

cyane  [Obolus],  (Billings) XX  VII:  4,  4a-b. 

Balmanella  multisecta  (Meek) Text  fig.  9,  p.  299. 

parva  (de  Verneuil) Text  fig.  10,  p.  299. 

subequata  (Conrad) Text  fig.  2.  p.  299. 

damesi  [Lingulella],  (Walcott) XXXIX:  8,  8a-c. 

dartoni  [Obolus  (Westonia)l,  Walcott Text    figs.    40A-C, 

p.  455. 

daunus  [EoorthLs],  (Walcott) XCV:  2,  2a-c. 

davidsoni  [Lingulella],  (Barrande) XXXII:  1,  la-e. 

davisi  [Lingulella],  (McCoy) XXX:  2,  2a: 

XXXI:  6,  Ga-h. 

Dearbornia  clarki  Walcott LXXXII:  7,  7a-d. 

decipiens  [Acrothele],  Walcott LVIII:  3,  3a-d. 

decipiens  [Obolus  mcconnelli],  Walcott XXIII:  4,  4a-b. 

definita  [-\crotreta],  Walcott LXIV:   2,  2a-g;    3, 

3a-b. 

Delgadella  lusitanica  (Delgado) XXIX:  5,  5a-b. 

delgadoi  [Lingulella],  Walcott XXIX:  6,  6a-c. 

depressa  [Acrotreta],  (Walcott) XLVI:  8,  8a-c. 

descendens  [.Acrotreta  ophirensis],  Walcott LXX  VIII:  1,  la-c. 

desiderata  [Elkanial,  (Billings) LI:  1,  la-d. 

desiderata  [Lingulella],  (Walcott) XX:  4, 4a-c;  5, 5a-j. 

desmopleura  [Eoorthis],  (Meek) XCVI:  1,  la-r. 

desmopleura  nympha[Eoorthis],  Walcott XCVI:  2. 

diablo  [Eoorthis?],  (Walcott) XCIII:  3. 

dice  [Billingsella],  Walcott CI:  S,  8a-d. 

Dicellomus  appalachia  Walcott LIU:  4, 4a-g. 


Dicellomus  nanus  (Meek  and  Ilayden) LIII:  1,  la-1;  2,2a, 

3, 3a-d. 

parvus  Walcott LXXXIX:  ll,lla-d. 

pectenoides  ( Whitfieldj LII:  6, 6a-c; 

Text    flgs.    48A-B, 
p.  575. 

politus  (Hall) LII:  1,  la-k;  2, 2a-i; 

3;  4,  4a;  5,  5a-b; 
Text    figs.    16A-B, 
p.314.and49A-B, 
p.  576. 

prolificus  Walcott 7 LXXXIX:  lQ,10a-b. 

sp.  undt.  Walcott LII:  7,  7a. 

dichotoma[..Vcrothele],  Walcott LX:  2. 

Discinolepis  granulata  Waagen LXXXI:  3, 3a-b. 

Discinopsis  gulielmi  (Matthew) LXXXII:  5. 5a-c. 

7  sulcatus  Walcott LXXXII:  G. 

discoideus  [Obolus],  (Hall and  Whitfield) XVIII:  G. 6a-d. 

dolatus  [  Obolus],  (Sardeson) Text    flgs.    35A-B, 

p.  390. 

doris  [Eoorthis],  (Walcott) XCVII:  13,  13a. 

dubia  [Lingulella],  (Walcott) XXIV':  4,4a. 

dubia  [  Siphonotrela],  Walcott LXXXI:7, 7a-b. 

dugaldensis  [Protorthis  (Loperia)],  Walcott XCIX:  5,5a-j. 

edsoni  [Rustella],  Walcott I:  l.la-e. 

eggegrundensis  [  Acrotreta],  Wmian LXX:  2a-d. 

eichwaldi  [  Oliolus),  Mickwitz Not  figured. 

elegans  [Obolus],  Mickwitz XV:  3. 

elegantula  [Curticia],  Walcott I:  2, 2a-l. 

elegantula  [  Eostrophoniena],  (Walcott) XCV:  6,Ga-b. 

Elkania  amhigua  (Walcott) LI:  2. 2a-c. 

desiderata  (Billings) LI:  1,  la-d. 

Ida  (Billings) XXX:  20, 20a; 

LI:  4,4a-c. 

ella  [Obolus(Weston!a)],  (Hall and  Whitfield) XXXIIl:  3.3a-c; 

XLVII:  l,la-p. 

ella  onaquiensis  [Obolus  (Westonia)],  Walcott XLIX:  G.6a. 

ellsi  [Lingulella],  (Walcott) XIX:  3,3a-c. 

elongata  [Obolella  crassa],  Walcott LV:  5,  Sa. 

elongatus  [Obolus  (Westonia)],  Walcott LXIII;  8,8a-d. 

emnionsi  [.Vcrotreta],  Walcott LXV:  6. 

endlichi  [Micromitra  sculptilis],  Walcott Text  fig.  22,  p.  342. 

Eoorthis  agreste  (Walcott) LXXXIX:  6. 6a. 

atava  (Matthew) XCV:  7, 7a-b. 

bavarica  ( Barrande) XCVII:  4. 

christianise  (Kjerulf) XCV:  1,  la-h. 

daunus  (Walcott) XCV:  2. 2a-c. 

desmopleura  (Meek) XCVI:  1.  la-r. 

desmopleura  nympha  (Walcott) XCVI:  2. 

7  diablo  (Walcott) XCIII:  3. 

doris  (Walcott) XCVII:  13, 13a. 

hastingsensis  (Walcott) XCI V:  3. 3a-c. 

iddingsi  (Walcott) XCI:  3, 3a-b. 

indianola  (Walcott) XCIV:  It,  2. 2a-h. 

johannensis  (Matthew) XCVII:  10,  10a. 

kayseri  (Walcott) XCVII:  6,  6a-b. 

kichouensis  (Walcott) LXXXIX:  5. 

linnarssoni  (Kayser) XCVII:  5,  5a. 

uewberryi  Walcott Te.xt    flgs.   69.\-D, 

p.  783. 

newtonensis  (Weller) XCVII:  9,  9a. 

pagoda  (Walcott) XCVII:  12,  12a-d. 

papias  (Walcott ) XCI:  4. 

primordialis(de  Verneuil  and  Barrande) XCVII:  1,  la-d. 

remnicha(Winchell) XCI:  1,  la-s; 

XCII:   2,   2a-d;    3, 

3a-e; 
Text  flg.  7,  p.  299. 

remnicha  sulcata  (Walcott) XCII:  1,  la-c. 

remnicha  te.xana  (Walcott) XCII;  4,  4a-g. 

remnicha  winfieldensis  (Walcott) XCI:  2,  2a-e. 

saltensis  (Kayser) XCVII:  11. 

tatei  (Etheridge) XCVII:  15, 15a. 

thyone  Walcott Text    figs.    70A-C, 

p.  789. 

tullbergi  (Walcott) XCV:  3. 

wichitaensis  (Walcott) XCIV:  1, la-o, lu. 

wichitaensis  laniusculus  (Walcott) XCIV:  Ip-s. 


356 


CA^IBRIAN  BRACHIOPODA. 


Boorthls  wlmanl  (Walcott) XCV:  4, -ta-d. 

zeno  Walcott Text    figs.    71A-B, 

p.  792. 

sp.  undt.  a  (Pompeckj) Not  figured. 

sp.  undt.  b  (Pompeckj) Not  figured. 

sp.  undt.  c  (Walcott) LXXXIX:7. 

sp.  undt.  d  Walcott LX XXIX :  8. 

sp.  undt.  e  Walcott Not  figiu-cd. 

Eostrophomcna  elegantula  (Walcott) XCV:  G,  Ga-b. 

eretla  [  Ni.'iiisla  ( Jamesclhi)],  Walcott CI:  5,  5a-b. 

eros  [Lingulella  (LingulepLs)],  (Walcott) XXXIX:  9,  9a. 

eryx  [.\crolheIe  matthewn],  Walcott LXI:  2. 

escasoni(0 bolus  (Westonia)],  (.Matthew) XLIX:  1,  la-f. 

esthonia  [.Schizambon?],  Walcott LXXXIV:  4. 

etheridgei(Huenella],  Walcott LXXXIX:  9,9a. 

etheridgei  [ Micromitra  ( Paterina)],  (Tate) Ill:  10.  lOa-c. 

euglyplius[Obolus  (Westonia)],  (Walcott) XLVIII:  1,  la-f. 

eurekensis[Orusia?],  (Walcott) CI:  7,  7a. 

excelsis  [Trematobolus],  Walcott LXXXII:  8,  8a-b. 

exigua  [Lingulella  (Lingulepis)],  (Matthew) XXXIII:  4,  4a; 

XLIII:  1,  la-z. 

exlmia  [Lingula?],  Barrande XXXII:  3. 

cxporrecta  [ Billingsella],  ( Linnarsson) LXXX VIII:  1,  la^l. 

exporrecta  rugosicostata  [ Billingsella],  Walcott LXXXVIII:  2,2a-c. 

favosa  [Obolella{Glyptias)],  (Linnarsson) LV:  2,  2a-d. 

feistmanteli[Obolus],  (Barrande) XII:  1,  la-f;  9,  9a. 

ferraginea  [Lingulella],  Salter XXIX:  1,  la-w; 

XXIX:  2,2a-f; 
XXX:  1; 
XXXI:  3,  3a-c; 
XXXV:  4,  4a-b. 

of.  ferruginea  [Lingulella],  Walcott XXX:  4. 

Jestinata[Nisusia],  (Billings) C:    1,  la-j;  2,  2a-c; 

Text  fig.  6,  p.  299. 

festinata  transversa  [Nisusia],  (Walcott) C:  4,  4a-b. 

finkelnburgi  [Finkelnburgia],  (Walcott) XCIII:  2,  2a-e. 

Flnkelnburgia  finkelnburgi  (Walcott) XCIII:  2,  2a-e. 

osceola  (Walcott) XCIII:  1,  la-h. 

osceola  corrugata  ( Walcott) Not  figured. 

finlandensis  [Obolus  (Westonia)J,  Walcott XLVIII:  3,  3a^b. 

flumenis  [Lingulella] ,  (Matthew) XXXV:  G,  6a-b. 

(Fordinia)  bellulus  [Obolus],  (Walcott) LI:  3,  3a-f. 

gilberti  [Obolus].  Walcott LI:  5,  5a-d. 

perfectus  [Obolus],  Walcott LXIII:  10,  lOa-d. 

formosa  [Mickwitzia],  (Wiman) VI:  3.  3a-c. 

fragilis  [Obolus],  (Walcott) XXIII:  5,  5a-e. 

frankUnensis  [Lingulella],  (Walcott) XXVI:  3,  3a-b. 

fuchsi  [Lingulella],  Redlieh XXXIX:  2,  2a-c;  3. 

gamagei  [.-Vcrothele],  (Ilobbs) LX:  5,  5a-c. 

gemma  [.Vcrotreta],  Billings LXVI:  1,  la-b. 

gemma  [Bicia],  (Billings) L:  1,  la-n. 

getmnula  [.Vcrotreta],  Matthew LXVJ:  3,  3a-c; 

LXXVII:  5,  5a-f. 

gilberti  [Obolus  (Fordinia)],  Walcott LI:  3,  5a-d. 

girtyi  [Linnarssonella],  Walcott LXXVIII:  5,  ,5a; 

LXXIX:  l.la^r. 

(Glyptias)  favosa  [Obolella],  (Linnarsson) LV:  2, 2a-d. 

gracia  [.Vcrotreta].  Walcott XL VI:  5,  5a-d. 

grandis  [Lingulella],  (Matthew) XXXVIII:  2,2a^f. 

grandis  (Lingulella  IrF-vis],  Matthew XIX:  4c. 

granulata  [  Vcrothele  (Redlichella)],  (Linnarsson)  .  .LVI:  2,  2a-n. 

granulata  [Botsfordia],  (Redlieh) LVII:  4,  4a~r. 

granulata  [Discinolepis],  Waagen LXXXI:  3, 3a-b. 

granulata  [Kutorgina],  Matthew V:  5,  5a-c. 

granvillensis  [Lingulella],  Walcott XXII;  1,  la-d. 

greg\va  [Lingulella  (Lingulepis)],  (Matthew) XLIV:  1,  la-p. 

gregwarobusta [Lingulella (Lingulepis)l, (Matthew). Not  figured. 

groomi  (Obolella],  Matley Text  fig.  52,  p.  596. 

gulielmi  [Discinopsis]  (Matthew) LXXXII:  5,  5a-c. 

harlanensis  [ Wimanella],  (Walcott) LXXXVII:  S, 5a-d. 

hastingsensis  [Eoorthls],  (Walcott) XCrV:  3,  3a-c. 

haydeni  (Micromitra),  Walcott Text   figs.    20.V-D, 

p.  33S. 

hayesi  [Lingulella],  (Walcott) XXV:  1,  la-j. 

hebertl  [Lingulella],  Barrois XXXIX:  ll,lla-c. 

helena  (Lingulella],  (Walcott) XXrV:3,3a-d. 

helena  [Protorthb],  Walcott XCIX:  4,  4a-b. 

Helmersenia  ladogensls  (.Teremejew) LXIII:  7,  7a-f. 

hera  [  Vcrothele  subsldua),  Walcott LX:  9. 


hlcksl  I  Billingsella],  (Salter  MS.)  (Davidson) XCVII:  7,  7a-f. 

highlandensis  (lijllingsella],  ( Walcott) LXXXVU:  4, 4st-c. 

HueneUa  abnormis  (Walcott) CIII:  2,2a-m; 

Text  fig.  13,  p.  299. 

bilUngsi  (Walcott) CII:  5,  Sa-c 

etheridgei  Walcott LXXXIX:  9,9a. 

lesleyi  Walcott Text  figs.  75.\-C, 

p.  807. 

orlentalis  ( Walcott) CI V :  3  :ia-b. 

texana  (Walcott) CIII:  l.la-L 

texana  licviusculus  (Walcott) Not  figured. 

vennontana  Walcott Text  fig.  70,  p.  809. 

humilUma  ( Lingulella?],  (Barrande) XXX:  12. 

hunnebergensis  |  Protorthis?],  Walcott XCV:  5,  3a-c 

ida  [Elkania],  ( Billings) XXX:  20, 20a; 

LI:  4,  4a-c. 

idahoensis  [.\crotreta],  Walcott LXV:  1,  la-i; 

LXVIII:  2,  2a-g. 

cf.  idahoensis  [ Acrotreta],  Walcott Not  figiu-ed. 

idahoensis  alta  [Acrotreta],  Walcott LXV:  4,  4a-b. 

idahoensis  sulcata  [Acrotreta],  Walcott LXV;  5. 

iddingsi  [Eoorthis],  (Walcott) XCI:  3,  3a-b. 

inchoans  [.Vcrotreta],  (Barrande) XV:  7,  7a. 

indianola  [EoorthLs],  (Walcott) XCIV:  It,  2,  2a^h. 

inflata  [Acrotreta],  (Matthew) LXX^^:  1,  la-k; 

2,2a. 

?  inflatus  (Obolus),  Westergird Not  figured. 

ingricus[Obolusapollinis],  (Eichwald) Not  figured. 

ino  [LinguleUa],  (Walcott) XX VI:  4,  4a-b. 

insiguis  [Trematobolus],  Matthew •. LXXXIV:  5,  5a-c 

insons  [Lingulella?].  (Barrande) XXXII:  2,  2a-e. 

insula;  [Lingulella atava],  (Matthew) XXXV:  8,  8a. 

intermedia  [.Vcrothele],  Linnarsson LVI:  3,  Sa-d. 

Inyoensis  [Wimanella],  Walcott Text  figs.  G3A-B, 

p.  747. 

iole [LinguleUa],  (Billings) XXVII:  5,5a. 

(Iphidella)  louise  [Micromitra],  Walcott Text  figs.  31 A-B, 

p.  359. 

nyssa  [Micromitra],  Walcott Ill:  9,  9a. 

omatella  [Micromitra],  (Linnarsson) Ill:  6,  Ga-d. 

pannula  [Micromitra],  (White) rV:  1,  la-t;  3,  3a; 

Text  fig.  32,  p.  36i 

parmula  maladensis  [Micromitra],  (Walcott).  .IV:  2,  2a-g. 

pannula ophirensis [Micromitra], (Walcott)...IV:  4,  4a-f. 

iphis  [Obolus  (Westonia)],  Walcott XLIX:  4,  4a-d. 

irene [LinguleUa],  (Billings) XXVII:  6,6a. 

iris  [  LinguleUa],  (BUlmgs) XXVII:  2. 

ismene  [Obolus],  Walcott XI:  3,  3a-b. 

Isse [LinguleUa],  (Walcotti XXXIX:  4,4a-b; 

Text  figs.  43A-F, 
p.  510. 
(JameseUa)  amii  [Nisusia],  Walcott CI:  G,  Ga-b. 

argent  a  [Nisusia],  Walcott CI:  9,  9a-b. 

erecta  [Nisusia],  Walcott CI:  5,  5a-b. 

?  kanabensis  [Nisusia]  Walcott Not  figtired. 

k-uthani  [Nisusia],  (Pompeckj) CI:  4,  4a-b. 

lowi  (Nisusia],  Walcott Text  figs.  Gl.\-D, 

p.  734. 

nautes  [Nisusia),  (Walcott) XCIII:  G,  6a-b. 

peUico[Nisusia],(deVemeuU and  Barrande).. XCVII:  2,  2a-b. 

perpast a  [Nisusia],  (Pompeckj) CI:  1,  la-h. 

perpasta  macra  [Nisusia],  (Pompeckj) CI:  3,  3a. 

perpastasubquadrata[Nisusia],  (Pompeckj). .CI:  2,  2a-b. 

spencei  [Nisusia],  (Walcott) XCIII:  7,  7a; 

Text  fig.  G2,  p.  737. 

utahensis[Nistisia].  Walcott CI:  10, 10a. 

jamesi[Plectorthis],  (HaU) XCVl:  5, 5a-c. 

johannensis [Eoorthis],  (Matthew) XCVII:  10, 10a. 

kanabensis  [Nisusia?  (JameseUa?)],  Walcott Not  figured. 

kayseri  [ Eoorthis],  (Walcott) XCVII:  6,  6a-b. 

kempanum  [Trematobolus],  (Matthew) LXXXIII:  1,  la-o. 

Keyserlingia  buchi  (de  Vemeuil) LXXXI:  4,  4a-e. 

kichouensis [Eoorthis],  (Walcott) LXXXIX:  5. 

kiurensis  [LinguleUa],  (Waagen) XXX:  S,  5a;  6, 6a. 

kuthani  [Nisusia  (JameseUa)],  (Pompeckj) CI:  4,  4a-b. 

kutorgaj  [Acrotreta],  Walcott LXV:  3,  ,3a-e,  g-k; 

Text  flg.  5S,  p.  692. 

Kutorgina  cingulata  (Billings) V:  1,  la-s; 

Text  flp.  3  and  8, 
p.299,and50A-C, 
p.  581. 


INDEX. 


357 


Kutorgina  granulata  Matthew V:  5,  5a-c. 

peculiaris  (Tate) V:  2. 

pemgata  VValcott V:  3,  3a-e. 

sardiniaensis  Walcott V':  4,  4a-c. 

sp.  undt.  Walcott Not  figured. 

labradorica  [Micromitra  ( raterina)],  (Billings) 11:2,  2a-f. 

labradoricaorientaiis[Micromitra(Paterina)],  (Wal- 
cott)  II:  2. 

labradorica  swaiitouensis  [Micromitra  (Paierina)], 

(Walcott) 11:  3,  3a-f. 

labradorica  utatiensis  [Micromitra  (Paterina)],(\^■al- 

cott) 11:  8,  Sa; 

Text  fig.  24,  p.  350. 
labradorica  var.  [Micromitra  (Paterina)]  Walcott..  .Not  figured. 

ladogensis  [Helmersenia],  (Jeremejew) LXIII:  7,  7a-f. 

Isevis  [ Acrothele  subsidua],  Walcott Not  figured. 

terts [Lingiilella],  Matthew XIX:  4,  4a-b. 

Iseris  grandis  [Lingulella],  Matthew XIX:  4c. 

l8e%-is  [Protorthis],  Walcott XCIX:  6,  6a-b. 

IfeWusculus  [Eoorthis  wichitaensis],  (Walcott) XCIV:  Ip-s. 

IgeWusculus  [Huenella  te.xana]  (Walcott) Not  figured. 

lamborni  [Obolus],  (Meek) XXII:  2,  2a-Q. 

lamborni  minimus  [Obolus],  (Walcott) XXV:  4.  4a-b. 

lamellosus  [Obolus  (Westonia?)],  (Barrande) XII:  7,  7a-d. 

lata  [Acrothele  matthewi],  Matthew LXI:  3. 

lateralis  [Syntrophia],  (Wtiitfleld) CII:  6,  Oa-g; 

Text  fig.  11,  p.  299. 

latourensis  [Protorthis],  (Matthew) XCIX:  3,  3a-d. 

leda  [Obolus  tetonensis],  Walcott Not  figured. 

lens  [Lingulella],  (Matthew) XXXIII:  1,  la-d. 

lens  [Obolus  ( Pateobolus)  bretonensis],  (Matthe%v).Not  figured. 

lenticularis  [Orusia],  (Wahlenberg) XCV'III:  1,  la-p;  2, 

2a-k;  3,  3a-b;  6, 
6a-d. 

lenticularis  atrypoides  [Orusia],  (Matthew) XCVIII:  5. 

lenticularis  lyncioides  [Orusia],  (Matthew) XCVIII:  4. 

leos  [tingulella],  (Walcott) XXIV:  2,  2a-c. 

lepis  [Lingulella],  (Salter) XXXI:  4,  4a-f. 

(Leptembolon)  lingulseformis  [Lingulella],   (Mick- 

witz) XIV:  5,  5a-b. 

lesleyi  [Huenella],  Walcott Te.xt  figs.  75A-C,  p. 

807. 

levisensis  [Acrothele],  Walcott LXXXI:  12,  12a-b. 

limoensis  [.\crotreta  uplandica],  (Wiman) LXX:  4,  4a-c. 

lindstromi  [Billingseila],  (Linnarsson) LXXXVII:  0,  Oa-f. 

lindstromi  [Obolella  ?],  Walcott LV:  4,  4a. 

lineolata  [Lingulella],  (Walcott) XLVIII:  2,  2a-l. 

Lingula  anatina  Brugui&re Text  figs.  34C-D,  p. 

374. 

Llngula  ?  exinila  Barrande XXXII:  3. 

lingulseformis  [Lingulella  (Leptembolon)],   (Mick- 

witz) XIV:  5,  5a-b. 

Lingulella  acutangula  ( Roemer) XVII:  1 ,  la-o. 

agnosforum  ( Wallerius) XXX:  15. 

ampla  (Owen) XXVIII:  1,  la-j. 

arguta  (Walcott) XXIV:  5. 5a-b. 

atava  (Matthew) XXXV:  5.5a-h. 

atava  insuire  (Matthew) XXXV:  8,8a. 

auga  ( W alcott) XX IV:  0,  6a-g. 

bella  ( Walcott) XIX:2,  2a-q; 

XXXVI:  4. 

bellula  (Walcott) XIX:  1 ,  la-e. 

billingsiana  (Whiteaves) XXIX:  3, 3a. 

bornemanni  (Walcott) XXX:  IS,  18a-c. 

buttsi  Walcott XXIX:  4,  4a-b. 

cania  (Walcott) XXX V:  3, 3a-d. 

cedens  ( Barrande) XXX:  8. 

clarkei  Walcott Text  figs.  42.\.-D,  p. 

486. 

coUlcia  (Matthew) XXXV:  1,  la-f:  2, 

2a-d. 

concinna  Matthew XXXIII:  2,  2a-h; 

XXXIV:  l,la-r. 

cuneola  (Whitfield) XXVII:  7,  7a-b. 

damesi  (Walcott) XXXIX:  8,  Sa-c. 

davidsoni  (Barrande) XXXII:  1,  la-«. 

davisi  (McCoy) XXX:  2,  2a; 

XXXI:  6, 6a-h. 


LinguleUa  delgadoi  Walcott XXIX:  6,6a-c. 

desiderata  ( Walcott) XX:  4, 4a-c;  5, 5a-j. 

dubia  (Walcott) XXIV:  4,  4a. 

ellsi  ( Walcott) XIX:  3, 3a-c. 

terruginea  Salter XXIX:  1,  la-w; 

XXIX:2,2a-f; 

XXX:  1; 

XXXI:  3,3a-c; 

XXXV:  4,  4a-b. 

of.  ferruginea  W^alcott XXX:  4. 

flumenis  (Matthew) XXXV:  0,  6a-b. 

franklinensis  (Walcott) XXVI:  3, 3a-b. 

fuchsi  Itedlich XXXIX:  2, 2a-c;  3. 

grandis  (Matthew) XXXVIII:  2,  2a-I. 

granvillensis  Walcott XX:  1 ,  la-d. 

hayesi  (Walcott) XXV:  1,  la-j. 

heberti  Barrois XXXIX:  11,  lla-c. 

helena  (Walcott) XXIV:  3,  3a-d. 

?  humiUuna  ( Barrande) XXX:  12. 

ino( Walcott) XXVI:  4,  4a-b. 

?  insons  (Barrande) XXXII:  2,  2a-e. 

iole  ( Billings) XXVII:  5,  5a. 

Irene  ( Billings) XXVII:  0,  6a. 

iris  (Billings) XXVII:  2. 

isse  (Walcott) XXXIX:  4, 4a-b; 

Text  figs.  43.\-F,  p. 
510. 

kiurensis  (Waagen) XXX:  5,  5a;  6,  6a. 

Ia3vis  Matthew XIX:  4,  4a-b. 

laevis  grandis  Matthew XIX:  4e. 

lens  (Matthew ) XXXIII:  1,  la-d. 

leos  (Walcott) XXIV:  2,  2a-c. 

lepis  (Salter) XXXI:  4,  4a-I. 

lineolata  (Walcott) XLVIII:  2, 2a-l. 

linnarssoni  (Walcott) XXX:  14, 14a. 

manticula  (White) XX:  1,  la-c. 

manticula  var Not  figured. 

martinensis  Matthew XXXVIII:  1,  la-& 

minor  (Matthew) XXXVII:  3,  3a-g. 

mosia  (Hall) XVIII:  1,  la-t. 

mosia  osceola  (Walcott) XVIII:  2, 2a-c. 

namio (Walcott) XXIV:  1 ,  la-d. 

nathorsti  Linnarsson XXXI:  1,  la-h. 

nicholsoni  Callaway XXX:  3,  3a-f. 

ora  (Walcott) XXXV:  9,  9a-d. 

oweni  (Walcott) X VIII:  5,  oa-f. 

perattenuata  (Whitfield) XXI:  1,  la-i. 

phaon  (Walcott) XXVI:  1,  la-e. 

pogonipensis  (Walcott) XX:  3,  3a-c. 

prima  (Conrad  MS.)  (Hall) XXVII:  1,  la-c 

?  prima?va  Hicks XXXI:  5,  5a. 

punctata  (Walcott) XX:  6,  6a. 

quadrilateralis  (Walcott) XXXIX:  6,  6a. 

radula  Matthew XLV:  1,  la-1. 

randomensis  (Walcott) XXI:  o,  5a. 

rotunda  ( Matthew) XXXVII:  3h-k. 

sehucherti  (Walcott) XXI:  6. 

siemiradzkii  (Walcott) XXXI:  2, 2a. 

signata  (Barrande) XXX:  11. 

similis  (Walcott) XXI:2,2a-i;3,3a-d. 

?  simplex  (Barrande) XXXII:  4,  4a-b. 

tarpa  (Walcott) XXIII:  2,  2a-c. 

texana  Walcott XLIX:  3,  3a. 

torrentis  ( Matthew) XXXV:  7. 

triparilis  (Matthew) XLV:  2,  2a-f; 

Text" figs.  44a-l, 
p.  537. 

tumlda  Matthew XXIV:  7,  7a-d. 

upis  (Walcott) XXXVI:  3,3a. 

wanniecki  Redlich XXXIX:  1,  la-n. 

welleri  (Walcott) XXXVIII:  4,  4a-b. 

Winona  (Hall) XVIII:  3,  3a-b. 

Winona  convexa  (Walcott) XVIII:  4,  4a-<l. 

wlrthi  (Barrande) XXX:  7. 

zeus  Walcott Text  fig.  45,  p.  541. 

sp.  undt.  a  Walcott XXX:  13. 

sp.  undt.  b  Walcott Not  figured. 

LinguleUa  (Leptembolon)  lingulseformis  (Mickwdtz)  XIV:  5, 5a-b. 


358 


CMIBRIAN  BRACHIOPODA. 


Llngulella  (Lingulepis)  acuminata  (Conrad) XXXIV:  3, 3a-e; 

XL:  1,  lar^; 
XLI:  1,  la-n; 
XLII:  l,la-o. 

acuminata  meeki  ( Walcott) XLI:  2, 2a. 

acuminata  sequcns  Walcott Text  flgs.  46 A-B , 

p.  5ol. 

eros  (Walcott) XXXIX:  9, 9a. 

exigua  (Matthew) XXXIII:  4,  4a; 

XLIII:  1,  la-z. 

gregwa  (Matthew) XLI V:  1,  la-p. 

grcgrvva  rol>usta  (.Matthew) Not  figured. 

longinerris  (Matthew) XLIV:  2, 2a-g. 

pumUa  (Matthew) XLV:  3,3a. 

7  pygmiea  (Salter) XXX:  10. 

roberti  (Matthew) XXXVII:  4, 4a-d. 

rowei  (Walcott) XXI:  4.4a-b. 

spatula  (Walcott) XIX :  5,  oa-b. 

?  squamosa  (Holl) XXX:  9. 

starri  (Matthew) XXXVII:  2,2a-b. 

?  sp.  undt.  (Walcott ) Not  figured. 

(Lingulobolus)  affinis  [Obolus], (Billings) XVI:  l,la-e. 

spissus  [Obolus],  (Billings) XVI:  2, 2a-k; 

XLII:  3,3a. 

Linnarssonella  girtyi  Walcott LXXVIII:  5, oa; 

LXXIX:  l,la-r. 

mmuta  (Hall  and  Whitfield) LXXIX:  2. 2a-b. 

modesta  Walcott LXXVIII:  8. 8a-f. 

nitens  Walcott LXXVIII:  7, 7a. 

tennesseensis  Walcott LXXIX:  3,3a-k. 

transversa  Walcott LXXVIII:  6. 6a-c. 

urania  Walcott LXXVIII:  9, 9a-c. 

linnarssoni  |Eoorthis],  (Kayser) XC VII:  S.  5a. 

linnarssoni  [Lingulella],  (Walcott) XXX:  14, 14a. 

lisani  | Acrotreta],  Walcott LX VIII:  3,  3a-c. 

loganilMicromitra(Paterina)],  (Walcott) II:  6.6a-b. 

longinervis  [Lingulella  (Lingulepis)],  (Matthew)...  .XLIV:  2, 2a-g. 

lopori  [Obolus],  Walcott IX :  4, 4a. 

( Loperia)  dugaldensis  ( Protorthis],  Walcott XCIX:  5, 5a-j. 

louise  [Micromitra  (Iphidella.i],  Walcott Te.xt    figs.    31.\-B, 

p.  359. 

lowi  [Xisusia  (Jamesella)],  Walcott Text   figs.  61.V-D, 

p.  734. 

lusitanica  [Delgadella],  (Delgado) XXIX:  5,5a-b, 

Iyncioides[Orusialenticularis],  (Matthew) XCVIII:  4. 

mcconnelli  [Obolus],  (Walcott) XXlII:3,3a. 

mcconnelli  decipiens  [Obolus],  Walcott XXIII:  4, 4a-b. 

mcconnelli  pelias [Obolus],  (Walcott) XXIII:  3b-c: 

XXXIX:  5,5a-c. 
macra  [Xisusia  (Jamesella)  perpasta],  (Pompeckj) .  .CI:  3,3a. 

maculata  [.\crothele],  (Salter) LVII:  2, 2a-b; 

LVIII:  2. 

mffira  [Obolus],  (Hall  and  Whitfield) X:  2, 2a-e. 

magna  [.Vcrotreta  sagittaUs],  (Matthew) LX VI:  4, 4a-f. 

major  [BillingseUa],  Walcott LXXXVI:  1,1a. 

major  [Micromitra  ( Paterina)],  (Walcott) Text  fig.  25,  p.  351 . 

major  [Rustella?],  (Matthew) Text  fig.  19,  p.  328. 

maladensis  [Micromitra  (Iphidella)  pannula],  (Wal- 
cott)   IV:  2, 2a-g. 

manitouensis  [Schizambon],  Walcott LXXXIV:  3,3a-e. 

manticula  [Lingulella],  (White) XX:  l,la-c. 

marion  [BillingseUa],  Walcott Text    figs.    67 A-B , 

p,  758, 

marjumcnsis  [.Vcrotreta],  Walcott LXXVIII:  2, 2a-d. 

martinensis  [Lingulella],  Matthew XXXVIII:  1,  la-g. 

matinalis  [Obolus],  (HaU) .VIII:  1,  la-k. 

matinalis  ?  (Obolus],  Walcott VIII:  3, 3a. 

mat thcwi  [ Acrothele],  (Tlartt) LXI:  1,  la-g. 

matthewi  eryx  [.Vcrothcle],  Walcott LXI:  2. 

matthewi  lata  [.\crothele],  Walcott LX  1:3. 

matthewi  multicostata  [.Vcrothcle],  Matthew LXI:  5, 5a-c. 

ma.\imus  [Obolus  apoUinis],  .Mickwitz VII:  9; 

XIV:  7, 7a. 
meekl  [Lingulella  (Lingulepis)  aciuninata],  (Wal- 
cott)  XLI:  2,2a. 

membranaceus  [Obolus],  Walcott Text  figs.  36.\-B, 

p.  4(Xi. 

meneghini  [Obolus?],  Walcott X.\.\ :  17,  17a. 

(Mickwilzella)  siluricus  [Obolus),  (Eichwald) XV:  1,  la-c. 

mickwiizi  [Obolus],  Walcott X:  1,  la-k. 


Mickwitzia  formosa  (Wiman) VI:  3, 3a-c. 

monililera  (Llnnarsson) VI:  1,  la-p; 

LIX:  2. 

occidens  Walcott VI:  4. 

pretiosa  Walcott VI:  2. 

7  sp.  undt.  Walcott Not  figured. 

Micromitra  alabamaensis  (Walcott) II:  5, 5a-c. 

haydeni  Walcott Text    flgs.   20.\-D, 

p.  338. 

nisus  (Walcott) II:  10. 

pealei  (Walcott) Ill:  3,  3a-e. 

pusilla  ( Llnnarsson) Ill:  2, 2a-c. 

scotica  Walcott Text  flgs.  21 A-C, 

p.  340. 

sculptilis  (Meek ) IH:  3, 5a-e. 

sculptilis  endlichi  Walcott Textflg.  22,  p.  342. 

zenobia  Walcott Text  fig.  23,  p.  :J42. 

sp.  undt.  (Walcott) Ill:  7. 

Micromitra  (Iphidella)  louise  Walcott Text   figs.    31.\-D 

p.  359. 

nyssa  Walcott Ill:  9, 9a. 

ornatella  (Llnnarsson) HI:  6, 6a-d. 

pannula  (White) IV:  I,  la-t;  3,3a; 

Text  fig.  32,  p.  362. 

pannula  maladensis  (Walcott) IV:  2,  2a-g. 

pannula  ophirensis  (Walcott) IV:  4,  4a-f. 

Micromitra  ( Paterina)  bella  (BilUngs) U:  1,  la-c. 

crenistria  (Walcott) Ill:  4,  4a-b. 

etheridgei  (Tate) '.  .Ill:  10,  lOa-c. 

labradorica  (Billings) II:  2,  2a-f. 

labradorica  orientalis  (Walcott) II:  11. 

labradorica  swantonensis  (Walcott) II:  3, 3a-f. 

labradorica  utahensis  (Walcott) U:  8,  8a; 

Textflg.  24,  p.  330. 

labradorica  var.  Walcott Not  figured. 

logani  (Walcott) II:  6, 6a-b. 

major  ( Walcott) Text  fig.  23,  p.  351. 

philhpsi  ( HoU) UI:  8. 

prospectensis  (Walcott) 11:  4,  4a. 

stissingensis  (Dwight) Ill:  1,  la-e. 

stissingensis  ora  Walcott Not  figured. 

stuarti  Walcott Text   figs.    2«.\-B, 

p.  333. 

superba  (Walcott) II:  7,  7a-f; 

Text    figs.    27.\-B, 
p.  333. 

undosa  (Moberg) Text    flgs.    28A-C, 

p.  356. 

waptaWalcolt Te.xt    flgs.    29.\.-B, 

p.  357. 

williardi  Walcott....'. II:  9b-c; 

Text    figs.    30.\-E, 
p.  33S. 

microscopica  [.\crolreta],  (Shumard) LXVII:  1,  la-h,  lo, 

2, 2a-d. 

microscopica  missouriensis  [Acrotreta],  Walcott LXVII:  4,  4a-b 

microscopica  tetonensis  [.Vcrotreta],  Walcott LXVII:  3,  3a-d. 

minima  [.\crotreta  7],  (Barrande) LXXVII:  7,7a. 

minimus  [Obolus],  Walcott XI:  S,  8a. 

minimus  [Obolus  lamborni],  (Walcott) XV:  4,  4a-b. 

minor  [.Vcrothyra],  Walcott LXX VI:  4, 4a-b, 

minor  [Lingulella],  (.Matthew)  XXXVII:  3,3a-g. 

minor  [Obolella],  (Walcott) LIV:  3,3a-d. 

minor  [Obolus?],  Barrande XV:  6. 

minuta  [  .V  crothele],  Walcott LXIU:  3. 

minuta  [Linnarssonella],  (Hall  and  Whitfield) LXXIX:  2,2a-b. 

miqueli  ( Vorkia?],  Walcott LXXXII:  4. 

mirandus  [Obolus?],  (Barrande) XII:  4,4a. 

misera  [Acrotreta],  (Billings) LXXII:  2,2a-L 

missouriensis  |  .Vcrotreta  microscopica),WaIcott LXVII:  4, 4a-U 

mobergi  [Obolella].  Walcott LV:  3. 3a-f. 

mode-sta  [Linnarssonella],  Walcott LXXVIII:  S,Sa-f. 

monilifera  [Mickwitzia],  (Llnnarsson) VI:  l,l3-p; 

LIX:  2. 

montanensis  [Clarkella],  (Walcott) CIV:  2,2a-d. 

mosia  [Lingulella],  ( Hall) XVIII:  1,  la-f. 

mosia  osceola  [Lingulella],  (Walcott) XVIII:  2,'2,">-c. 

multicost<ita  [Vcrothele  matthewi],  Matthew LXI:  5.5a-c. 

multisecta  [Dalmanella],  (Meek) Text  fig.  9,  p.  299. 

murrayi  [Obolus?],  Billings XV:  12, 


INDEX. 


359 


namouna  (Obolus],  Walcott VIII:  2, 2a. 

nanno  [Lingulella],  ( Walcott) XXIV:  1 ,  la-d. 

nanus  [Dicellomus],  (Meek  and  Hayden) LIII:  l,la^l;  2,  2a; 

3.3ar-d. 

nathorsti  [Lingulella],  Linnarsson XXXI:  l.la^h. 

nautes  [Nisusia  (Jamesella)],  (Walcott) XCIII:  6, (ia-b. 

neboensis  [Acrotrcta],  Walcott LXXVII:  9, 9a-b. 

Neobolus  warthi  Waagen I:  3;  4,4a-b;  5.5a; 

LXXXI:  2,2a-h; 
Text   figs.    47.\-B, 
p.  567. 

newberryi  [Eoorthis],  Walcott Te.xt  figs.  C9.V-D, 

p.  783. 

newtonensis  [Eoorthis],  ( Weller) XCVII:  9, 9a. 

nicbolsoni  [Acrotreta],  Davidson LXXIII:  l,la-k;  C, 

Ca-b. 

nicbolsoni  [Lingulella],  Callaway XXX:  3,3a-f. 

ninus  [Obolus  tetonensis],  Walcott VIII:  11,  lo; 

XI:  l,lar-g. 

nisus  [Micromitra],  (Walcott) II:  10. 

Nisusia  alberta  (W'alcott) C:  3,3a-d. 

corapta  (Tate) XCVII:  14. 

lestinata  (Billings) C:  l,lar-j;  2,2a-c: 

Te.xt  fig.  6,  p.  299. 

lestinata  transversa  (Walcott) C:  4, 4a-b. 

rara  Walcott Text  fig.  60,  p.  730. 

?vaticina(de  Vemeuil  and  Barrande) XCVII:  3,3a^b. 

Nisusia  (.lamesella)  amii  Walcott CI:  6.  Tia-b. 

ai  genta  Walcott CI:  9. 9a-b. 

erccta  Walcott. ..'. CI:  5.5a-b. 

7  kanabensis  Walcott Not  figured. 

kuthani  ( Pompeckj ) CI:  4. 4a-b. 

lowiWalcott Text   figs.    Ol.V-D, 

p.  734. 

nautes  (W'alcott) XCIII:  0,  (ia-b. 

pellico  (de  Verneuil  and  Barrande) XCVII:  2,2a-b. 

perpasta  (Pompeckj) CI:  l,la-li. 

perpasta  macra  (Pompeckj) CI:  3, 3a. 

perpasta  subquadrata  (Pompeckj) CI:  2.2a-b. 

spencei  (Walcott) XCIII:  7, 7a; 

Text  fig.  U2,p.  737. 

utahensis  Walcott CI:  10. 10a. 

sp.  undt.  Walcott Not  figiKed. 

nil  ens  [  Linnarssonella],  Walcott LXXVIII:  7, 7a. 

nitida  [.\crothelel,  ( Ford) LVIII:  4,  4a. 

notchensis  [Obolus  (Westonia)),  Walcott LXIII:  9. 

nox  [Acrotreta],  Walcott LXXVII:  10. 

nundina  [Obolus],  Walcott XI:  4,  4a. 

nundina[Syntrophial,  Walcott CII:  4,  4a-d. 

nyuipha[Eoortliis  desmopleura],  (Walcott) XCVI:  2. 

nyssa  [Micromitra  (Iphidella)],  Walcott Ill:  9,  9a. 

Obolella  asiatica  Walcott LV:  C,  Ca. 

atlantica  Walcott LV:  la-i; 

Text  fig.  51,  p.  590. 

chromatica  Billings LIV:  1,  la-i. 

crassa  (HaU ) LI V :  2,  2a-n ; 

Text  fig.  14,  p.  299. 

crassa  elongata  Walcott LV:  5,  5a. 

groomi  Matley Text  fig.  52,  p.  596. 

?  lindstromi  Walcott LV:  4,4a. 

minor  (Walcott) LIV:  3,  3a-d. 

mobergi  Walcott LV:  3,  3a-f. 

vcrmilionensis  Walcott Text  figs.  53A-E , 

,  p.  598. 

wirrialpensis  Etheridge LV:  7,  7a-b. 

Obolella  (Glyptias)  favosa  (Linnarsson) LV:  2,  2a^d. 

Obolus  acadicus  Walcott XI:  5. 

"?advenus  Barrande XII:  5,  5a-b. 

anceps  Walcott X:  3,  3a-f. 

?ancillus  (Barrande) XII:  2. 

apoUinis  Eichwald VIl:  1-8, 10-1 

XIV:  6,  Ga; 
Text  figs.  4  and  15, 
p.  299. 

apoUinis  ingricus  ( Eichw.ald) Not  figured. 

apoUinis  maximus  Mickwitz .-...VlI:  9; 

XIV:  7,  7a. 

apoUinis  quenstedti  (Mickwitz) Text  figs.  34.\-B, 

p.  .374. 


Obolus?  bavaricus  (Barrande) XV:  10, 10a. 

belli  (BiUings) XXXVIU:  3,  ,3a-b. 

chinensis  (Walcott) XXXIX:  7,  7a-b. 

complexus  Barrande XII:  3, 3a;  8,  8a. 

cyane(BUlings) , XXVII:  4,  4a-b. 

discoideus  (Hall  and  Whitfield) XVIII:  6,  Ca-d. 

dolatus  (Sardeson) Text  figs.  3oA-B, 

p.  390. 

eichwaldi  Mickwitz Not  figured. 

elegans  Mickwitz XV:  3. 

leistmanteli  (Barrande) XII:  l,la-f;  9,9a. 

fragilis  (Walcott) XXIII:  5,  5a-e. 

?  inflatus  Westergird Not  figured. 

isniene  Walcott XI:  3,  3a^b. 

lamborni  (Meek) XXII:  2,  2a-n. 

lamborni  minimus  (Walcott) XXV:  4,  4a-b. 

loperi  Walcott IX:  4,  4a. 

mcconnelli  (Walcott) XXIH:  3,  .3a. 

mcconnellidecipiens  Walcott XXIII:  4,  4a-b. 

mccoimeUi  pelias  (Walcott) XXIII:  3b-c. 

XXXIX:  5,  5a-c. 

mtera  (HaU  and  Whitfield) X:  2,  2a-e. 

matinalis  (Hall) VIII:  1,  la-k. 

matinalis?(lIaU)  Walcott VIII:  3,  .la. 

membranaceus  Walcott Text  figs.  36A-B, 

p.  403. 

?meneghini  Walcott XXX:  17, 17a. 

mickwitzi  Walcott X:  1,  la-k. 

minimus  Walcott XI:  8,  8a. 

?  minor  Barrande XV:  6. 

?  mirandus  (Barrande) XII:  4, 4a. 

?  murrayi  BUlings XV:  12. 

namouna  Walcott VIII:  2, 2a. 

nundina  Walcott XI;  4,  4a. 

obscurus  Walcott XI:  9,  9a-d. 

?  palliatus  Barrande XV:  5. 

pandemia  Walcott IX:  3, 3a-d. 

panderi  Mickwitz Not  figiu-ed. 

parvus  Walcott Text    figs.  37A-B, 

p.  408. 

pheres  Walcott XI:  6,  Ca-b. 

prindlei  (Walcott) XXVII:  3,  3a-e. 

refulgens  Matthew IX;  2,  2a-d. 

rhea  Walcott ^ IX:  1,  la-c. 

V  rokitzanensis  Barrande XII:  6. 

rotundatus  (Walcott) XX:  2,  2a-e. 

schmalenseei  (Walcott) XXX:  19, 19a-e. 

Schmidt i  Mickwitz XV:  lla-c. 

selwj-ni  (Matthew) XXXVI:  1,  la-h;  2, 

2a-b; 

XXXVn:  l,la-f. 
sept.alis  (Walcott) XXIII:  3d; 

XXXTV:  2,  2a. 

shansiensis  Walcott XI:  7,  7a-e. 

since  (Walcott) XXVI:  2, 2a-h. 

smithi  Walcott Text    figs.    38A-B, 

p.  416. 

tetonensis  Walcott IX:  5,  5a-d. 

tetonensis  leda  Walcott Not  figured. 

tetonensis  ninus  Walcott VIII:  1  l-lo; 

XI:  1,  la-g. 

?  torrentis  Matthew Not  figured. 

triangularis  Mickwitz Not  figured. 

volborthi  Mickwitz Not  figured. 

wUlisi  (Walcott) XXIII:  1,  la-j. 

wortheni  Walcott IX:  5e; 

Text  figs.    39.A.-D, 
p.  421. 

zetus  (Walcott) XXV:  3,  3a-c. 

?  zoppi  Walcott XXX:  16, 16a-b. 

sp.  undt.  a  Walcott X:  4. 

sp.  undt.  b  Walcott Not  figm-ed. 

sp.  undt.  c  Walcott Not  figured. 

sp.  undt.  d  Walcott Not  figtired. 

sp.  undt.  e  Kayser XV:  S. 

?sp.  undt.  f  Kaj-ser XV:  9. 

sp.  undt.  g  Linnarsson Not  figured. 

Obohis  (Acritis)  antiquissimus  (Eichwald) XIII:  3: 

XV:  2,  2a-d. 


360 


CAMBRIAN  BRACHIOPODA. 


Oboliis  ( Acritis?)  niRatiis  Walcott X II I:  2  and  3. 

Obolus(Broggeria)salteri(IIoll) XIII;  1,  la-n; 

XV:  4,  4a-d. 
Obolus  Fordlnia  bellulus  (Walcott) LI:  3:  3a-f. 

gilberli  Walcott LI:  5,  5a-d. 

perfectus  Walcott LXIII:  10,10a-d. 

Obolus  (Lingulobolus;  afTinis  (Billings) XVI:  1,  la-c. 

spissus( Billings) XVI:  2,  2a-k; 

XLIl:  3,3a. 

Ol)()liis(Mickwitzella)siliiricus(Eichwald) XV:  1,  la-c. 

Oboliis(Fal3eobolus)  bretoneiLsis  (Matthew) XXXII:  5,  5a-g. 

bretonensis  lens  (Matthew) Not  figured. 

Obolus  (Schmidtia)  acuininatus  Mickwitz XIV:  2  2a-c. 

celatus (Volborth) XIV:  1,  la-c. 

crassus  Mickwitz XI V:  4,  4a-d. 

obtu.sus  Mickwitz XIV:  3,3a-c. 

Olwlus  (Westonia)  &landensis  Walcott XLVIII:  6,6a. 

aurora  (HaU) XLVI:  1 ,  la-h. 

balticus  Walcott XLVIII:  7.7a-b. 

blaekwelderi  Walcott XXX IX:  10, lOa-c. 

bottnicus  ( Wiman) XLVIII:  4, 4a-c. 

chuarensis  (Walcott) XXV:  2,2a-e. 

dartoni  Walcott Text    figs.    40A-C, 

p.  465. 

ella  (HaU  and  Whitfield) XXXIII:  3, 3a-c; 

XLVII:  l,la-p. 

ella  ouaquiensis  Walcott X  LIX:  6, 6a. 

elongatus  Walcott LXIII;  8, Sa-d. 

escasoni  (Matthew) XLIX:  l,la-f. 

euglyphus( Walcott) XLVIII;  l,la-I. 

flnlandensis  Walcott XLVIII:  3, 3a-b. 

iphis  Walcott XLIX:  4,4a-d. 

1  lamellosus  (Barrande) XII:  7.7a-d. 

notchensis  Walcott LXIII:  9. 

rogersi  (Walcott) XLII:  2,2a-d. 

stoneanus  (Whitfield) XXVIII:  2, 2a-g; 

XLIX:  2,2a. 

themis  Walcott XI:  2.2a-c. 

wasatchensis  Walcott XLIX:  5, 5a: 

Text  figs.  41A-F, 
p.  467. 

wimani  Walcott XLVIII:  5, .la-b. 

sp.  undt.  a  Walcott Not  figured. 

sp.  undt.  b  Walcott Not  figured. 

obscura[BillingseIla].  Walcott LXXXVI:  G. 

obscurus  [Obolus] ,  Walcott XI;  9, 9a-d. 

obtusus  [Obolus  (Schmidtia)],  Mickwitz XIV:  3,3a-c. 

occidens  [Mickwitzia],  Walcott VI:  4. 

oelandica  [Acrotreta],  Westergird Not  figured. 

onaquiensis [Obolus  (Westonia)  ella],  Walcott XLIX:  6,6a. 

ophirensis  [ Acrotreta] .  Walcott LXXIV:  1,  la-p. 

ophirensis  [Micromitra  (Iphidella)  pannula],  (Wal- 
cott)   IV:  4, 4a-f. 

ophirensis  descendens  [Acrotreta],  Walcott LXXVIII;  1 ,  la-c. 

ophirensis  rugosa  [Acrotreta],  Walcott LXXIV:  2,2a-e. 

ora  [Lingulella],  (Walcott) XXXV:  9,9a-d. 

Orbiculoidea  contraria  ( Barrande) LXXXI;  9. 

pileolus  ( Hicks  MS.)  (Salter) LXXXI:  11 ,  11a. 

varians  (Barrande) LXXXI:  8. 

orientalLs  [  Billingsella],  ( Whitfield) LXXXVI:  2, 2a-b. 

orientalis  [ Huenella],  (Walcott) CIV:  3.3a-b. 

orientalis  [Micromitra  (Paterina)  labradorica],  (Wal- 

cott> II:  2. 

orientalis  [  Vorkia?] ,  Walcott LXXXII:  3, 3a. 

ornatclla  [Micromitra  (Iphidella)].  (Linnarsson) III:  G.6a-d. 

orta  [.\crothyra  signata],  Matthew LXXX;  3, 3a-b. 

orthia  [Syntrophia],  Walcott CIV:  4,4a-b. 

Orusia  1  eurekensis  (Walcott) CI:  7, 7a. 

lenticularis  ( Wablenberg) XCVIII:  1 .  la-p;  2, 

2a-k;   3,3a-b;   6, 
6a-c. 

lenticularis  atrypoides  (Matthew) XC  VI II:  5. 

lenticularis  lyncioides  (Matthew) XCVIII:  4. 

osceola  [  Finkelnburgia] ,( Walcott) XC  I II:  I ,  la-h. 

osceola  [ Lingulella  mosia] ,  ( Walcott) XVIII:  2, 2a-c. 

osceola  corrugata  [  Finkelnburgia],  (Walcott) Not  figured. 

Otusia sandbergi ( Winchell) XCll I:  4, 4a-d. 

utahensis  Walcott LXXXIX:  3, 3a-c. 

ovalis  [.Vcrotreta],  Walcott XLVI:  2, 2a-b. 


oweni  [Lingulella],  (Walcott) XVIII:  5,5a-f. 

pacifica (Acrotreta),  Walcott LXIX:  6, Oa-e. 

pagoda  [Ko»rthLs],(Walcottj XCVII:  12,12a-d. 

(Palffiobolus)  bretonensis[Obolu.s],  (Matthew) XXXII:  5,5a-g. 

bretonensis  lens  [Obolus],  (Matthew) Not  figured. 

palliatus  [Obolus  ?],  Barran'lc XV:  5. 

pandemia  [Obolus],  Walcott IX:  3,3a-d. 

panderi  [.\crot hele],  Walcott LIX:  5,5a-c. 

panderi  [Obolus],  Mickwitz Not  figured. 

pannula  [Micromitra (Iphidella)],  (White) IV:  l,la-t;  3, .3a; 

Text  fig.  32,  p.  362. 
pannula  maladensis  [Micromitra  (Iphidella)],  (Wal- 
cott)   IV:  2,  2a-g. 

pannula  ophirensis  [Micromitra  (Iphidella)],  (Wal- 
cott)   IV:  4, 4a-f. 

papias[Eoorthis],  (Walcott) XCI:  4. 

parva  [Dalmanclla],  (dc  Vcrneuil) Text  fig.  10,  p.  299. 

pari-a  [ I'lecturt his),  ( Dalman) XCVI:  6,(ia-g. 

par\-ula[.\crolr(!ta],  (Wallerius) LXXVII:  4.1a. 

pan'US[Dicellomus],  Walcott LXXXIX:ll,ll»-d. 

parvus  [Obolus].  Walcott Te.xt    figs.    37A-B, 

p.  408. 

(Paterina)  bella  [Micromitra],  (Billings) II:  1,  la-c. 

crenistria [Micromitra], (Walcott) Ill:  4,4a-b. 

etheridgei  [Micromitra],  (Tate) Ill:  10,  lOa-c. 

labradorica  [Micromitra],  (Billings) LI:  2,2a-L 

labradorica    orientalis   [Micromitra],    (Wal- 
cott)  II:  2. 

labradorica  swantonensis  [Micromitra],  (Wal- 
cott)  II:  3,3a^L 

labradorica    utahensis    [Micromitra],    (Wal- 
cott)  II:  8,8a; 

Text  fig.  24,  p.  3Sa 

labradorica  var.  [Micromitra],  Walcott Not  figiu'ed. 

logani  [Micromitra],  ( Walcott) II:  6, 6a-b. 

major  [Micromitra],  (Walcott) Text  fig.  25,  p.  351. 

phillipsi  [Micromitra],  ( Iloll) Ill:  8. 

prospectensis  [Micromitra],  (Walcott) II:  4.4a. 

stissingensis  [Micromitra],  (Dwight) Ill:  1,  la-e. 

stissingensis  ora  Walcott Not  figured. 

stuarti  [Micromitra],  Walcott Text   figs.    26A-B, 

p.  3.55. 

sui)erba  [Micromitra]  (Walcott) II:  7, 7a-I; 

Text    figs.    27A-B, 
p.  355. 

undosa  [Micromitra],  (Moberg) Te.xt    figs.    28A-C, 

p.  356. 

wapta  [Micromitra],  Walcott Text   figs.   29A-B, 

p.  357. 

williardi  [Micromitra],  Walcott II;  9b-o; 

Text  figs.     30A-E, 
p.  358. 

pealei  [Micromitra],  (Walcott) Ill:  3, 3a-e. 

pectenoides  [Dicellomus],  (Whitfield) Lll:  6,  Oa-c; 

Text    figs.    48A-B, 
p.  575. 

peculiaris  [Kutorgina],  (Tate) V  :  2. 

pelias  [Obolus  mcconnelli],  (Walcott) XXIII:  3b-c; 

XXXIX:  5,5a-c. 
peUico[Xisusia(Jamesella)],  (de  Verneiiil  and  Bar- 
rande)   XCVI  1 :  2. 2a-b. 

perattenuala  [Lingulella],  (Whilfielii) XXI:  1,  la-i. 

perfect us(Obolus(Fordinia)],  (Walcott) LXIII:  10. lOa-d. 

perpasta  [Xisusia  (.lamesella)],  (Pompeckj) CI:  l.la-h. 

perpastamacra[.\isusia(Jamesella)],  (Pompeckj)  ..CI:  3.3a. 
perpasta  subquadrata  [Nisusia  (Jamesella)],  (Pom- 
peckj)  CI:  2.2a-b. 

penigata  [Kutorgina],  Walcott V:  3, 3a-€. 

phaon[Lin'.;ulella].  (Walcott) XXVI:  l.la-e. 

pheres  [Obolus],  ^\alcot  t XI:  6.  Ca-b. 

Philhedra  Columbiana  ( Walcott) LXXXI;  10. 

phillipsi  [Micromitra  (Paterina)),  (lloIl) Ill:  8. 

pileolus  [Orbiculoidea],  (Salter) LXXXI;  11, 11a. 

Plectorthis  jamcsi  (Hall) XC\"I;  5,  5a-c. 

parva  (Dalman) XCVI:  6,  6a-g. 

plicatella  (Hall) XCVI;  4,  4a; 

Text  fig.  12,  p.  299. 
whitfleldi  (N.  II.  Wincheli) XCVI:  3. 


INDEX. 


361 


plicatclla  [Billingsella],  Walcott LXXXVI:  3,  3a-n; 

Text  fig.  1,  p.  299. 
plicatella[PleotortliisJ,(Hall) XCVI:  4,4a; 

Text  fig.  12,  p.  299. 

pogonipensis  [LingulellaJ,  (Walcott) XX;  3,  3a-c. 

politus  (DicellomusI,  (Hall) LII;  1,  la~k;  2,  2a-i; 

3;  4,  4a;  5,  5a-b; 

Text  figs.  16A-B, 
p.314,and49A-B, 
p.  576. 

pretiosa  [ Acrothele],  (Billings) LVIII:  1,  la-g. 

pretiosa  [Mickwitzia],  Walcott VI:  2. 

prima  [Acrothele),  (Matthew) LXI:  6,  6a-b; 

LXII:  2. 

prima  [Acrothyrasignata],  Matthew LXXX:  2,  2a-b. 

prima  ILiugulellaJ,  (Conrad  M.S.)  (Hall) XXVII;  1,  la-c. 

prima  costata  [Acrothele],  (Matthew) LXI;  4,  4a-d. 

primiEva  [Acrothele],  (de  Verneuil  and  Barrande).-LVII:  6. 

prim8eva[Acrotrcta],  Walcott LXIX:  1,  la-f. 

primscva  [Lingulella?]. Hicks XXXI:  5.  5a. 

priinordialis[Eoorthis],  (de  Verneuil  and  Barrande).XCVII:  1,  la-d. 

primordialis  [Syntrophia],  (Whitfield) CII;  2,  2a-e. 

primordialis  argia  [Syntrophia],  Walcott CII;  3. 

prindlei  [Obolus],  ( Walcott) XXVII:  3,  3a-e. 

priscus[Schizambon].  Matthew LXXXIV:  2,  2a-e. 

pristinus  [Trematobolus],  (Matthew) LXXXIII:  2, 2a-h; 

LXXXIV:  6. 
proavia  [Acrothyra],  (Matthew) LXXV:  3; 

LXXVI:  3,  3a-u. 

proles  (Acrothele),  Matthew LXII:  3,  3a-c;  4,4a. 

prohflcus  [DiccIIomus],  Walcott LXXXIX;10,10a-b. 

prospectensis  [Micromitra  (Paterina)],  (Walcott). .  .II:  4,  4a. 

Protorthis  bilhngsi  (Hartt) XCIX:  1,  la-g. 

helcna  Walcott XCIX:  4,  4a-b. 

?  hunnebergensis  Walcott XCV;  5,  5a-c. 

laivis  Walcott XCIX:  6,  6a-b. 

latourensis  (Matthew) XCIX;  3,  3a-d. 

quacoensis  (Matthew) XCIX;  2,  2a-e. 

wingi  Walcott XCIII;  5,  5a-c. 

sp.  undt.  Walcott Not  figured. 

Protorthis  (Loperia)  dugaldensis  Walcott XCIX;  5,  5a-j. 

pulchra[Botsfordia),  (Matthew) LXII;  5,  5a-l. 

pumila  [Lingulella  (Lingulepis)],  (Matthew) XLV:  3,  3a. 

pimipellyi  [Billing.sclla].  Walcott XCVII:  8.  8a-c. 

punctata  [Lingulella],  (Walcott) XX;  6,  6a. 

pusilla  [Micromitra],  (Linnarsson) Ill:  2,  2a-c. 

puteis  [Acrothele  avia],  Matthew Not  figured. 

pygma;a  [Lingulella  (Lingulepis)],  (Salter) XXX;  10. 

pyxidicula  {.\crotreta].  White LXIX;   2,    2a-f;    3, 

3a-f. 

'  quacoensis  [Protorthis],  (Matthew) XCIX:  2.  2a-e. 

quadrilateralis  [Lingulella],  (Walcotlj XXXIX:  6,  6a. 

quadrilineata  [Acrothele],  Pompeckj LVII:  5. 

Quebecia Circe  (Billings) CIV:  7,  7a-g. 

quenstedti  [Obolus  apollinis],  (Mickwitz) Text    figs.    34A-B, 

p.  374. 

radula  [Lingulella],  Matthew XLV;  1,  Ia-1. 

randomensis  [Lingulella],  (Walcott) XXI;  5,  5a. 

rara  [Acrothele),  (Walcott) LXIII:  4, 4a. 

rara  [Nisusia],  Walcott Text  fig.  60,  p.  730. 

recurva [ Volborthia),  ( Kutorga) I:  6. 6a-e; 

Text   figs.  33A-B, 
p.  36B. 
(Redlichella)  granulata  [.\crothele),  (Linnarsson). ..LVI:  2,2a-n. 

refulgens [Obolus),  Matthew IX:  2, 2a-d. 

remnichafEoorthis],  (N.  H.  Winohell) XCI;  l,la-s; 

XCII:  2.  2a-d;  3, 
3a-e; 

Text  fig.  7,  p.  299. 

remnicha  sulcata  [Eoorthis],  (Walcott) XCII:  1.  la-c. 

remnicha texana [Eoorthis),  (Walcott) XCII:  4. 4a-g. 

remnicha  winfieldensis  [Eoorthis),  (Walcott) XCI:  2, 2a-e. 

retrodexa [Billingsella),  (Matthew) XC;  1.  la-h. 

rhea [Obolus),  Walcott IX:  1,  la-c. 

richthoteni  [Billingsella),  Walcott LXXXIX:  I. 

roberti  [Lingulella  (Lingulepis)],  (Matthew) XXXVII:  4. 4a-d. 

robusta[Lingulella  (Lingulepis)  gregwa],  (Matthew). Not  figured. 

rogersi [Obolus ( Westonia)],  (Walcott) XLII:  2, 2a-d. 

rokitzanensis [Obolus?),  Barrande XII:  6. 

romingeri  [Billinssella],  (Barrande) XC:  2,2a-n. 


rotunda  [Lingulella] ,  (Matthew) XXXVII:  3h-k. 

rotundata  [Syntrophia],  Walcott CIII;  4, 4a-e. 

rotundatus  [Obolu.s],  (Walcott) XX:  2, 2a-e. 

rowei  [Lingulella  ( l.ingulopis)],  (Walcott) XXI:  i,  4a-b. 

rudis  [ Acrotreta] ,  Walcott LX V:  3f; 

LXXV:  1. 

rugatus  [Obolus  (Acritis?)),  Walcott XIII:  2  and  3. 

riigosa  [Acrotreta  ophirensis],  Walcott LXXPV':  2. 2a-e. 

rugosa[Schizopholis),  Waagen I:  4c; 

LXXXI;  l.la-c. 

rugosicostata  [Billingsella  exporrecta],  Walcott LXXXVIII:  2,2a-c. 

Rustella  edsoni  Walcott I:  1.  la-e. 

?  major  (Matthew) Text  fig.  19,  p.  328. 

sabrinai  [Acrotreta],  (Callaway) LXXIII:  5, 5a-d. 

saflordi  [Wimanella],  (Walcott) LXXXVII;  7,7a. 

sagittalis  [Acrotreta],  (Salter) : LXXI:  2,  2a-h;  3, 

3a-j. 

cf .  sagittalis  [Acrotreta] Not  figHred. 

sagittalis  magna  [Acrotreta),  (Matthew) LX VI:  4. 4a-f. 

sagittalis  taconica  [Acrotreta),  (Walcott) LXXI:  l,Ia-o. 

sagittalis  transversa  [Acrotreta),  (Hartt) LXXII:  l,la-k. 

salemensis  [Billingsella),  (Walcott) LXXXVII: 3. 3a. 

saltensis [ Eoorthis),  (Kayser) XCVII:  11. 

salteri  [Obolus  (Broggeria)],  (HoU) XIII:  l,la-n; 

XV:  4,4a-d. 

sandbergi  [Otusia],  (N.  H.  Wincbell) XCIII:  4,  4a-d. 

sardiniaensis  [  Kutorgina],  Walcott V:  4. 4a-c. 

Schizambon?  csthonia  Walcott LXXXIV:  4. 

manitouensis  Walcott LXXXI\':  3. 3a-e. 

priscus  Matthew LXXXIV';  2. 2a-e. 

typicalis  Walcott LXXXIV:  l,la-d. 

Schizopholis  rugosa  Waagen I;  4c: 

LXXXI;  l.la-c. 

schmalenseei  [Acrotreta],  Walcott LXX:  1.  la-s. 

schmalenseei  [Obolus],  (Walcott) XXX;  19. 193-e. 

schinidti  [Obolus],  Mickwitz XV:  lla-c. 

(Schmidtia)  acuniinatus  [Obolus],  Mickwitz XIV;  2. 2a-c. 

celatus  [Obolus],  ( Volborth) XIV:  1, la-c. 

crassus  [Obolu.s),  Mickwitz XFV':  4. 4a-d. 

obtusus  [Obolus],  Mickwitz XIV;  3. 3a-c. 

schucherti  [Lingulella],  (Walcott) XXI:  6. 

Schuchertina  Cambria  Walcott LI:  6,  6a-m, 

scotica  [Micromitra],  Walcott Text    figs.    21A-C, 

p.  340. 

sculpt  ills  [Micromitra],  (Meek) Ill:  5,  5a-e. 

sculpt  ills  cndlichi  [Micromitra],  Walcott Text  fig.  22,  p.  342. 

secbachi  [Acrotreta],  Walcott LXX VII:  3,  3a. 

selwyni  [Obolus],  (Matthew) XXXVI;  1,  la-h;  2, 

2a-b; 
XXXVII:  1,  la-f. 

septalis  [Obolus],  (Walcott) XXXIV:  2,  2a; 

XXIII:  3d. 
sequcns  (Lingulella  (Lingulepis)  aciuninata],  Wal- 
cott  Text    figs.    46A-B, 

p.  551. 

sera  [Acrothyra],  (Matthew) LXXX:  i,  4a-c;  5, 

5a-d;    6,  6a-i;    7, 
7a-b;  8?. 

shansiensis  [Obolus],  Walcott XI:  7,  7a-c. 

shantungcnsis  [Acrotreta],  Walcott LXIX;  5,  oa-e. 

shelbyensis  [Wimanella],  Walcott II:  9,  9a. 

siemiradzkii  [Lingulella],  (Walcott) XXXI:  2,  2a. 

signalis  [Acrotreta],  Walcott LXIX:  4. 

signata  (Acrothyra],  Matthew LXXX:  1,  la-d. 

signata  [Lingulella],  ( Barrande) XXX:  11. 

signata  orta  [Acrothyra),  Matthew LXXX:  3,  3a-b. 

signata  prima  [.\crothyra],  Matthew LXXX:  2,  2a-b. 

siluricus  [Obolus  (Mickwitzella)].  (Eichwald) XV:  1,  la-c. 

similis  [Lingulella],  (Walcott) XXI:2.2a-j;3,3a-d. 

simplex  [Lingulella'?],  (Barrande) XXXII:  4,  4a-b. 

simplex  [Wimanella],  Walcott LXXXIX:  2,  2a-e; 

Text  fig.  64,  p.  748. 

since  [Obolus],  (Walcott) XX VI:  2,  2a-h. 

Siphonotreta  dubia  Walcott LXXXI:  7,  7a-b. 

unguiculata  (Eichwald) LXXXI:  6,  6a-e. 

verrucosa  (Eichwald) LXXXI:  S,  5a-b. 

smithi  [Obolus],  Walcott Text    figs.    38A-B, 

p.  416. 

socialis  [Acrotreta],  von  Seebach...'. LXXIII:  3,  3a-c;  4. 

4a-e. 


362 


CAMBRIAN  BRACIIIOPODA. 


spatula  [LinfruIeUa(Lingiilcpis)],  (Walcott) XIX:  5,  5a-b. 

spcncei  [Nisusia  CJamesella)],  (Walcott) XCIIl;  7,7a; 

Textrig.«2,  p.  737 

spinosa  [Acrotreta],  Walcott LXXIX:  4, 4a-g. 

spissus  [Obolus  (Lingulobolus)],  (Billings) XVI:  2,  2a-k; 

XLII:  3,  3a. 

spurri  [ Acrothele],  Walcott LX :  3,  3a-c. 

squamosa [Lingulella  ( Lingulepis  7)],  (Hall) XXX:  9. 

starri  [Lingulella  (Lingulepis)],  (Matthew) XXXVII:  2,  2a-b. 

stoneanus  [Obolus  ( Westonia)],  (Whitfield) XXVIII:  2,  2a-g; 

XLIX:  2,  2a. 

stissingensis  [Micromitra  ( Paterina)],  (Dwight) Ill:  1,  la-e. 

sti-ssingensis  ora  Walcott Not  figured. 

striata  [Billingsella],  Walcott LXXXVI:  4,  4a-c. 

stuarti  (Micromitra  (Paterina)],  Walcott Text    figs.  26.\-B, 

p.  S.W. 

subconica  [Acrotreta],  Kutorga LXXIII:  2,  2a-i. 

subciiuata  [Balmanella],  (Conrad) Text  fig.  2,  p.  299. 

subquadrata  [Nisusia  (Jamesella)  perpasta],  (Pom- 

peckj) CI:  2,2a-b. 

subsidua  [.Verothele],  (White) LX:  1,  la-o;  8. 

subsiduahera  [.Vcrothele],  (Walcott) LX:  9. 

subsidua  liT>vis  [.Vcrothele],  Walcott Not  figured. 

sulcata  [.Vcrotreta  idahoensis],  Walcott LX V:  5. 

sulcata  [Eoorthis  reninicha],  (Walcott) XCII:  1,  la-c. 

sulcatus [Discinopsis?],  Walcott LXXXII:  6. 

superba [Micromitra  (Paterina;],  (Walcott) II:  7,  7a-f; 

Text    figs.    27A-B, 
p.  355. 
swantonensis  [Micromitra  (Paterina)  labradorica], 

(Walcott) 11:3,  3a-f. 

Swantonia  antiquata  (Billings) CIV:  5,  5a-b. 

weeksi  Walcott CIV:  0. 

Syntrophia  alata  Walcott CIII:  3, 3a-d. 

baral>uensis  (A.  Winchell) CII:  1,  la-g. 

calcilera  (Billings) CIV:  1,  la-i. 

Cambria  Walcott Text    figs.    72A-D, 

p.  800. 

campbeUi  Walcott Text     flp.  73A-F, 

p.  801. 

lateralis  (Whitfield) CII:  6,0a-g; 

Text  fig.  11,  p.  299. 

nundina  Walcott CII:  4,  4a-<l. 

orthia  Walcott CIV:  4,  4a-b. 

primordialis  (Whitfield) CII:  2,  2a-e. 

primordialis  argia  Walcott CII:  3. 

rotimdata  Walcott CIII:  4,  4a-e. 

?  unxia  Walcott Text  fig.  74,  p.  805. 

taconica [Acrotreta  sagittalis],  (Walcott) LXXI:  1,  la-o. 

tarpa  [Lingulella],  (Walcott) XXIII:  2,  2a-c. 

tatei[ Eoorthis].  (Etheridge) : XCVII:  15,  1.5a. 

tennesseensis [ Linnarssonella],  Walcott LXXIX:  3,  3a-k. 

tetonensis [.Vcrotreta  microscopica],  Walcott LXVII:  3,  3a-d. 

tetonensis[ Obolus],  Walcott IX:  5,  5a-d. 

tetonensis  leda  [Obolus],  Walcott Not  figured. 

tetonensis  ninus  [Obplus],  Walcott VIII:  1 1-lo; 

XI:  1,  la-e. 

texana  [Eoorthis  remnicha],  (Walcott) XCII:  4,  4a-g. 

texana  [  Iluenella],  (Walcott) CIII:  1,  la-i. 

texana  beviusculus  [Iliienolla],  (Walcott) Not  figured. 

texana  [  Lingulella],  Walcott X  LIX:  3,  3a. 

themis [Obolus  (Westonia)],  Walcott XI:  2,  2a-c. 

thyone  [Eoorthis],  Walcott Text    figs.    70A-C, 

p.  789. 

torrentis[LingulelIa],  (Matthew) XXXV:  7. 

torrentis[Otiolus?],  Matthew Not  figured. 

transversa  [.Vcrotreta  sagittalis],  (Ilartt) LXXII:  1,  la-k. 

transversa[ Linnarssonella],  Walcott LXXVIll:  6,  6a-c. 

transversa  (Nisusia  (est  inata],  (Walcott) C:  4,  4a-b. 

Trematobolus excelsis  Walcott LXXXII:  8, 8a-b. 

insignis  Matthew LXXXI V:  5,  .'ja-c. 

kempanum  (Matthew) LXXXIII:  1,  la-o. 

pristinus  (Matthew) LXXXIII:  2,  2a-h; 

LXXXIV:  0. 

triangularis[Obolns],  Mickwitz Not  figured. 

triparilis  [  Lingulella],  (Matthew) X  LV:  2,  2a-f; 

Text     figs.      44a-/, 
p.  .537. 
tullbergi [Eoorthis],  (Walcott) XCV:  3. 


tumida  [Lingulella],  Matthew XXIV:  7,7a-<l. 

turner!  (AcrotheleJ,  Walcott LX:  7,  7a. 

typicalis[.Schizamtjon],  Walcott LXXXIV:  1,  la-d. 

ulrichi  I  Acrotreta],  Walcott LXXVIII:  3. 

nndosa  [Micromitra  (Paterina)],  (Mobcrg) Text    flgs.    28A-C, 

p.  3S«. 

unguiculata  [Siphonotreta],  (Eichwald) LXXXI:  fi,  Ga-e. 

unxia  [Syntrophia],  Walcott Text  fig.  74,  p.  SOS. 

upis  [ Lingulella],  (Walcott) XXXVI:  3,  3a. 

uplandica  [ .Vcrotreta],  Wiman hXK:  3,  .'ia-c. 

uplandica  lim6ensis[. Vcrotreta],  (Wiman) LXX:  4,  4a-c. 

Urania  [Linnarssonella],  Walcott LXXVIII:  9, 9a-c. 

utabensis    [Micromitra    (Paterina)    labradorica), 

Walcott II:  8, 8a; 

Text  ng.  24,  p.  350. 

utahensis  [Nisusia  (Jame.sella)],  Walcott CI:  10, 10a. 

utahensis  (Otusia],  (Walcott) LXXXI.V:  3,  Sa-c. 

varians  [Orbiculoidea],  (Barrande) LXXXI:  8. 

vatiiina  (Nisusia  ?],  (de  v'erneuil  and  Barrande). ..XCVII;  3,  3a-b. 

vermilionensis  (Obolclla),  Walcott Text    figs.    53A-E, 

p.  rm. 

vermontana  [Iluenella],  Walcott Text  fig.  711,  p.  809. 

verrucosa  [Siphonotreta],  (Eichwald) LXXXI:  5,  .Oa-b. 

viliaboimensis  [Acrothelc],  Delgado Not  figured. 

volborthi  [Obolus],  Mickwitz Not  figured. 

Volborthia  recur\'a  (Kutorga) I:  6,  6a-e; 

Text    flgs.    aiA-B, 
p.  300. 

wanneri  (Yorkia),  Walcott LXXXII:  l,la-i. 

wanniecki  (Lingulella],  Redlich XXXIX:  I,  la-n. 

wapta  [Micromitra  ( Paterina)],  Walcott Text  figs.     29.\-B, 

p.  357. 

wart  hi  [Neobolus],  Waagen..^. I:  3;  4,  4a-b;  5,  5a; 

LXXXI:  2,  2a-h. 
Text    flgs.    47A-B, 
p.  507. 

warthi  [Wynnia],  (Waagen) LXXXIX:  4,   4ar.f; 

Text  fig.  m,  p.  771. 

wasatchensis  [Obolus  (Westonia)],  Walcott XLIX:  5,  .5a; 

Te.xt    flgs.    41.\-F, 
p.  407. 

washingtonensis  [Yorkia?],  Walcott LXXXII:  2,  2a. 

weeksi  [Swantonia],  Walcott CIV:  0. 

welleri  [Lingulella],  (Walcott) XXXVIII:  4,  4a-b. 

(Westonia)  ilandensis  [Obolus),  Walcott XLVIII:  C,  i.a. 

aurora  [Obolus],  (Hall) XLVI:  1,  la-h. 

bait icus  (Obolus],  Walcott XLVIII:  7,  7a-b. 

blackivelderi  (Obolus],  Walcott XXXIX:  10,  lOa-c. 

bottnicus  [Obolus],  (Wiman) XLVIII:  4,  4a-c. 

chuarensis  [Obolus],  (Walcott) XXV:  2,  23-e. 

dartoni  [Obolus;],  Walcott Text    figs.    40A-C, 

p.  455. 

clla  [Obolus),  (Hall  and  Whitfield) XXXIII:    3,    .3a-c; 

XLVH:  1,  la-p. 

ellaonaquiensis[Obohisl,  Walcott XLIX:  0, 1'a. 

elongiitus  [Obolus],  Walcott LXIII:  8.  8a-d. 

escasoni  [Obolus],  (.Matthew) XLIX:  1,  la-f. 

cuglyplms  [Obolus],  (Walcott) XL.VIII:  1,  la-f. 

finlandensis  [ObolusJ.  Walcott XLVIII:  3,  .'ia-b. 

iphis  (Obolus],  WaJcott XLIX:  4,  4a-d. 

?  hunellosus  ((Jbolus  7],  ( Barrande) XII:  7,  7a-d. 

notchensis  [Obolus],  Walcott LXIII:  9. 

rogersi  [Obolus],  ( Waicott) XLII:  2,  2a-d. 

stoneanus  [OImIus],  (Whitfield) XXVIII:  2,  2a-g; 

XLIX:  2,2a. 

themis  [Obolus],  Walcott XI:  2,  2a-c. 

w;isatehensis  [Obolus],  Walcott XLIX:  5,5a; 

Text    figs.    41A-F, 
p.  4lw. 

wimani  [Obolus],  Walcott XLVIII:  5,  5o-b. 

whilejivesi  [Bicia],  Walcott L:  2,  2a-e. 

whitfieldi  [ liillingsella),  ( Walcott) LXXXVI:  S,  Sa. 

whitficldi  [Plectorthis].  (.N.  H.  Winchell) XCVI:  ,3. 

wichitaensis  [Eoorthis],  (Walcott) XCI V:  1 , la-o, lu. 

wiehitaensis  Iieviusculus  lEoorlhis],  (Walcott) XCIV':  Ip-s. 

williardi  [Micromitra  (Paterina)],  Walcott II:  9b-<'; 

Text    figs.    30A-E, 
p.  .m. 

willisi  [Obolus],  (Walcott) X.XIII:  l,la-j. 

Wimanella  ?  anomala  (Walcott) L.XXXVII:  1,  la-«. 


INDEX. 


363 


Wimanella  harlanensis  CWalcott) LXXXVII:  5, 5a-d. 

inyoensjs  Walcott Text    figs.    B3A-B, 

p.  747. 

saflordi  (Walcott) LXXXVII:  7, 7a. 

shelbyensis  Walcott 11 :  9, 9a. 

simplex  Walcott LXXXIX:  2, 2a-e; 

Text  flg.  64,  p.  748. 

■wlmani  [Obolus  (Westonia)],  WaJcott XLVIII:  5, 5a-b. 

wimani  [Eoorthis],  (Walcott) XCV:  4,4a-d. 

winfieldensis  [Eoorthis  remnicha],  (Walcott) XCI:  2, 2a-e. 

wingi  [Protorthis],  Walcott XCIII:  5. 5a-c. 

Winona  [Ltngulella],  (Hall) X VIII:  3. 3a-b. 

winona  convexa  [Lingiilella],  (Walcott) X^'I1I;  4.4a-d. 

wirrialpensis  [Obolella],  Etheridge hV:  7.7a-b. 

wirthi  [Lingulella],  (Barrande) XXX:  7. 

woodwortlii  [Acrothele],  Walcott LX:  0. 


wortheni  [Obolus],  Walcott IX:  5e; 

Text    flgs.    39A-D, 
p.  421. 

Wynnia  warthi  (Waagen) LXXXIX:  4,4a-f: 

Textflg.  68,  p.  771. 

yorkensis  [Acrothele],  Walcott LIX:  4.4a-b. 

Yorkia?  miqueli  Walcott LXXXII:  4. 

7  orientalis  Walcott LXXXII:  3, 3a. 

wanneri  Walcott LXXXII:  1,  la-i. 

?  washing! onensis  Walcott LXXXII:  2,2a. 

zeno  [Eoorthis],  Walcott Text    figs.    7IA-B, 

p.  792. 

zenobia  [Micromitro],  Walcott Text  fig.  23,  p.  342. 

zetus  [Obolus],  (Walcott) XXV:  3..3a-e. 

zeus  [Lingulella],  Walcott Text  fig.  4.5,  p.  541. 

zoppi  [Obolus?],  M'alcott XXX:  16,  lOa-b. 


o 


